CN113302547A

CN113302547A - Display system with time interleaving

Info

Publication number: CN113302547A
Application number: CN202080008150.0A
Authority: CN
Inventors: 严谨; 李晓凯; Y·C·杨
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2019-08-13
Filing date: 2020-08-03
Publication date: 2021-08-24
Also published as: WO2021030093A1; EP3874320A1

Abstract

An electronic device such as a head mounted device may have a display that produces a display image. The head-mounted device may have an optical system that merges a real-world image from a real-world object with a display image. The optical system provides real world images and display images to the eye-box for viewing by a user. The optical system may use time interleaving techniques and/or polarization effects to combine the real-world image and the display image. Switchable devices such as polarization switches and tunable lenses may be controlled in synchronization with the frames of the display image. A geometric phase lens may be used that exhibits different lens powers for different polarizations of light.

Description

Display system with time interleaving

Priority of the present application is claimed in U.S. patent application No. 16/935,083 filed on 21/7/2020, U.S. patent application No. 16/935,080 filed on 21/7/2020, U.S. provisional patent application No. 62/886,172 filed on 13/8/2019, and U.S. provisional patent application No. 62/886,171 filed on 13/8/2019, which are hereby incorporated by reference in their entirety.

Background

The present disclosure relates generally to electronic devices, and more particularly to electronic devices having an optical system for merging display content and real-world content.

Electronic devices sometimes include a display. For example, a wearable electronic device, such as a head-mounted device, may include a display for displaying computer-generated content overlaid on real-world content. The optical system is used to merge real world content and display content.

Challenges may arise in providing a satisfactory optical system for merging real-world content and display content. If careless, problems with optical quality and other performance characteristics may arise.

Disclosure of Invention

Electronic devices, such as head mounted devices, may have displays that produce display images. The head-mounted device may have an optical system through which a user with an eye in the eye box may view real-world objects. During operation, the optical system may be used to merge a real-world image from a real-world object with a display image.

The display may generate images per frame. Different objects may be displayed in alternate image frames. The optical system may be adjusted in synchronization with the alternating image frames to display different objects at different focal planes.

In some configurations, an optical system may have an intensity switch formed from a pair of linear polarizers and an interposed polarization switch. The polarization switch may be operated in a first state in which linearly polarized light of a given polarization is not rotated by the polarization switch and a second state in which linearly polarized light of the given polarization is rotated by 90 °.

Additional components may be incorporated into the optical system, such as front and rear biasing lenses having complementary lens powers, a polarization switch to facilitate combining real world images and display images in a time-interleaved manner, and a geometric phase lens that exhibits different lens powers for images having different polarizations. The tunable lenses may be used to place the display images at different respective focal plane distances from the eye box.

Drawings

Fig. 1 is a schematic diagram of an illustrative electronic device, such as a head-mounted display device, according to an embodiment.

Fig. 2 is a top view of an exemplary head-mounted device according to an embodiment.

Fig. 3A and 3B are cross-sectional views of exemplary optical systems with time-staggered and tunable lenses according to embodiments.

Fig. 4A, 4B, 5A, 5B, and 6-9 are cross-sectional side views of exemplary optical systems with geometric phase lenses according to embodiments.

Detailed Description

The electronic device may include a display and other components for presenting content to a user. The electronic device may be a wearable electronic device. A wearable electronic device, such as a head-mounted device, may have a head-mounted support structure that allows the head-mounted device to be worn on a user's head.

The head mounted device may include a display for displaying visual content to a user. The head-mounted device may also include an optical system that assists the user in viewing real-world objects while viewing the display content. The optical system may include an optical component that combines real world image light with image light associated with an image displayed by the display. When both real-world image light and display image light are visible to the user, the head-mounted device may place computer-generated objects within the physical environment surrounding the user.

Real world content may be merged with display content using time division multiplexing, polarization multiplexing, and/or other arrangements for combining light from real world objects with light from a display.

A schematic diagram of an exemplary system that may include a head-mounted device with an optical system for merging real-world content with display content is shown in fig. 1. As shown in fig. 1, system 8 may include one or more electronic devices such as electronic device 10. The electronic devices of system 8 may include computers, cellular telephones, head-mounted devices, wrist-watch devices, and other electronic devices. Configurations in which the electronic device 10 is a head-mounted device are sometimes described herein as examples.

As shown in fig. 1, an electronic device, such as electronic device 10, may have control circuitry 12. Control circuitry 12 may include storage and processing circuitry for controlling the operation of device 10. The circuitry 12 may include storage devices such as hard disk drive storage devices, non-volatile memory (e.g., electrically programmable read only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random access memory), and so forth. The processing circuitry in control circuit 12 may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application specific integrated circuits, and other integrated circuits. Software codes may be stored on storage devices in the circuit 12 and run on processing circuits in the circuit 12 to implement the method for the apparatus10 (e.g., data acquisition operations, operations involving the use of control signals to adjust components of the apparatus 10, etc.). The control circuit 12 may include wired and wireless communication circuits. For example, control circuit 12 may include radio frequency transceiver circuitry, such as cellular telephone transceiver circuitry, wireless local area networks

Transceiver circuitry, millimeter wave transceiver circuitry, and/or other wireless communication circuitry.

During operation, communication circuitry of devices in system 8 (e.g., communication circuitry of control circuitry 12 of device 10) may be used to support communication between electronic devices. For example, one electronic device may transmit video and/or audio data to another electronic device in system 8. The electronic devices in system 8 may communicate over one or more communication networks (e.g., the internet, a local area network, etc.) using wired and/or wireless communication circuitry. The communication circuitry may be used to allow device 10 to receive data from and/or provide data to external equipment (e.g., tethered computers, portable devices such as handheld or laptop computers, online computing equipment such as remote servers or other remote computing equipment, or other electrical equipment).

The device 10 may include an input-output device 22. Input-output devices 22 may be used to allow a user to provide user input to device 10. Input-output circuitry 22 may also be used to gather information about the environment in which device 10 operates. Output components in circuitry 22 may allow device 10 to provide output to a user and may be used to communicate with external electrical equipment.

As shown in fig. 1, input-output circuitry 22 may include one or more displays such as display 14. In some configurations, display 14 of device 10 includes left and right display devices (e.g., left and right components such as left and right scanning mirror display devices, liquid crystal on silicon display devices, digital mirror devices, or other reflective display devices, left and right display panels based on arrays of light emitting diode pixels (e.g., organic light emitting display panels, or display devices based on arrays of pixels formed from crystalline semiconductor light emitting diode dies), liquid crystal display panels, and/or other left and right display devices aligned with the left and right eyes of a user, respectively.

Display 14 is used to display visual content for a user of device 10. The content presented on the display 14 may include virtual objects and other content provided to the display 14 by the control circuitry 12, and may sometimes be referred to as computer-generated content, display images, display lights, and the like. The computer-generated content may be displayed in the absence of real-world content or may be combined with real-world content. In some configurations, a real-world image may be captured by a camera (e.g., a forward-facing camera), such that computer-generated content may be electronically overlaid on portions of the real-world image (e.g., where device 10 is a pair of virtual reality goggles with an opaque display). In other configurations, an optical system (e.g., an optical coupling system) may be used to allow computer-generated content to be optically overlaid on top of a real-world image. By way of example, device 10 may have a see-through display system that provides a computer-generated image to a user through a beam splitter, prism, holographic coupler, or other optical coupler, while allowing the user to view real-world objects through the optical coupler.

The input-output device 22 may include the sensor 16. The sensors 16 may include, for example, three-dimensional sensors (e.g., a three-dimensional image sensor such as a structured light sensor that emits a light beam and acquires image data for a three-dimensional image from a light spot generated when a target is illuminated by the light beam using a two-dimensional digital image sensor, a binocular three-dimensional image sensor that acquires three-dimensional images using two or more cameras in a binocular imaging arrangement, a three-dimensional lidar (light detection and ranging) sensor, a three-dimensional radio frequency sensor, or other sensor that acquires three-dimensional image data), cameras (e.g., infrared and/or visible light digital image sensors), gaze tracking sensors (e.g., gaze tracking systems based on image sensors and, if desired, light sources that emit one or more light beams that are tracked using image sensors after reflection from a user's eyes) _ or, Touch sensors, buttons, capacitive proximity sensors, light-based (optical) proximity sensors, other proximity sensors, force sensors, sensors such as switch-based contact sensors, gas sensors, pressure sensors, humidity sensors, magnetic sensors, audio sensors (microphones), ambient light sensors, microphones for capturing voice commands and other audio inputs, sensors configured to capture information about motion, position, and/or orientation (e.g., accelerometers, gyroscopes, compasses, and/or inertial measurement units including all or a subset of one or both of these sensors), radio frequency sensors to determine the location of other devices (and thus the relative position of such devices with respect to device 10), and/or other sensors.

User input and other information may be collected using sensors and other input devices in the input-output device 22. If desired, the input-output devices 22 may include other devices 24 such as tactile output devices (e.g., vibrating components), light emitting diodes and other light sources, speakers for producing audio output such as ear speakers, and other electronic components. Device 24 may include one or more adjustable optical components, such as a liquid crystal device or other electrically adjustable optical components. These components may form a polarization switch. The polarization switch, which may sometimes be referred to as an electrically tunable waveplate or an electrically controllable polarization rotator, may be adjusted to rotate linearly polarized light by different amounts (e.g., by 0 ° or 90 °) depending on the state of the switch. If desired, a polarization switch may be used with a pair of polarizers to form an electrically adjustable shutter (sometimes referred to as a light modulator or intensity switch). Device 24 may include a tunable lens if desired. The tunable lens may be formed from liquid crystal devices and other electrically tunable devices. The tunable lens may be adjusted to produce different lens powers (e.g., a desired positive lens power and/or negative lens power) and/or to adjust the lateral position of the lens center (e.g., to accommodate different user gaze directions). For example, the tunable lens may be adjusted to move the position of the center of the lens based on information collected in real time from the line-of-sight detection system.

If desired, the device 10 may include circuitry for receiving wireless power, circuitry for wirelessly transmitting power to other devices, batteries and other energy storage devices (e.g., capacitors), joysticks, buttons, and/or other components.

The electronic device 10 may have a housing structure (e.g., housing walls, straps, etc.), as shown by the illustrative support structure 26 of fig. 1. In configurations in which the electronic device 10 is a head-mounted device (e.g., a pair of glasses, a visor, a helmet, a hat, etc.), the support structure 26 may include a head-mounted support structure (e.g., a helmet shell, a headband, a temple in a pair of glasses, a visor shell structure, and/or other head-mounted structure). The head-mounted support structure may be configured to be worn on the head of a user during operation of the device 10, and may support the display 14, sensors 16, other components 24, other input-output devices 22, and the control circuitry 12.

Fig. 2 is a top view of electronic device 10 in an exemplary configuration in which electronic device 10 is a head-mounted device. As shown in FIG. 2, electronic device 10 may include a support structure 26 for use in receiving components of device 10 and in mounting device 10 on a user's head. These support structures may include, for example, structures that form the housing walls and other structures of the head unit (e.g., support structure 26-2), as well as additional structures such as straps, temples, or other supplemental support structures (e.g., support structure 26-1) that help retain the head unit and components of the head unit on the user's face so that the user's eyes are located within the eye box 60.

Display 14 may include left and right display portions (e.g., sometimes referred to as left and right displays, left and right display devices, left and right display components, or left and right pixel arrays). The optical system of device 10 may be formed by coupler 84 (sometimes referred to as an input coupler), waveguide 86, and an optical system formed by one or more optical components, such as

components

100 and 102. The component 100 may be interposed between the front (outward facing) side of the device 10 and the waveguide 86 (e.g., between the real world object 90 and the waveguide 86). A component 102 may be interposed between waveguide 86 and the rear (inward facing) side of device 10 (e.g., between waveguide 86 and eyebox 60). The

components

100 and 102 may include fixed and/or adjustable components that help place the computer-generated content at a desired focal plane and help optically merge the content with the real-world image passing through the

components

100 and 102 and the waveguide 86 to the eye box 60. A user with eyes in eye box 60 can view real world objects through the optical system formed by components 100,

waveguide

86 and 102, as well as other components of device 10, while viewing overlapping computer-generated content from display 14.

As shown in FIG. 2, the left portion of the display 14 may be used to create an image for the left-eye box 60 (e.g., where the left-eye image is viewed by the user's left eye). The right portion of display 14 may be used to create an image for right-hand eye box 60 (e.g., where the user's right eye views the right-hand image). In the configuration of FIG. 2, left and right portions of display 14 may be formed by respective left and right display devices (e.g., digital mirror devices, liquid crystal on silicon devices, scanning MEMS mirror devices, other reflective display devices, or other displays).

Optical couplers 84 (e.g., prisms, holograms, etc.) may be used to couple the respective left and right images from the left and right display portions into the respective left and right waveguides 86. The image may be guided within the waveguide 86 according to the principles of total internal reflection. In this way, left and right images may be transmitted from the left and right sides of the device 10 toward a location in the center of the device 10 that is aligned with the left and right eye boxes 60. The waveguide 86 may be provided with respective left and right output couplers 88, such as holograms formed on or in the material of the waveguide 86. Left and right output couplers 88 may couple left and right images from the left and right waveguides 86, respectively, toward the left and right eye boxes 60 for viewing by a user. This allows the user to view a computer-generated image (display image), such as computer-generated object 92 overlaid over a real-world object, such as real-world object 90.

By adjusting the lenses and other optical components in components 100 and/or 102, the distance from device 10 at which display image 92 is focused for viewing by the user from eye box 60 may be adjusted. These adjustments may be made without affecting the focus of real world objects, such as real world object 90. In this way, real-world objects such as real-world object 90 may be observed by the user as if device 10 were not present (e.g., without any intermediate optical components), while computer-generated content such as virtual object 92 may be placed at one or more desired distances from the user within the scene that the user is viewing.

Time interleaving and polarization control techniques may be used to combine real-world content and display content in the optical system of device 10.

As an example, consider the time division multiplexing arrangement of fig. 3A. Fig. 3A is an illustration of an exemplary optical system (optical system 122) that may be used for both the left-hand and right-hand portions of device 10. As shown in fig. 3A, system 122 includes an external optical component, such as optical component 100, and an internal optical component, such as optical component 102. The electrically adjustable devices in components 100 and/or 102 are controlled by control circuit 12. Waveguide 86, and in particular, the portion of waveguide 86 having output coupler 88, is interposed between

components

100 and 102. The real world image light 104 passes through the system 122 and is viewable by the user's eyes at the eye box 60. Computer generated image light (display light) 124 is directed to output coupler 88, through waveguide 86 to output coupler 88. Output coupler 88 couples light 124 out of waveguide 86 such that light 124 passes through component 102 to eye box 60.

System 122 has offset

lenses

106 and 120. The powers of the offset

lenses

106 and 120 may be complementary. For example, the offset lens 106 may have a positive lens power, such as 1.5 diopters, and the offset lens 120 may have a negative lens power, such as-1.5 diopters. With this type of arrangement, the positive power of the lens 106 is offset by the corresponding negative power of the lens 120, so that the net effect is as if there were no lens between the real world object and the eye box 60 (e.g., the real world image 104 experiences zero lens power from the

lenses

106 and 120 when traveling to the eye box 60). At the same time, the negative power of lens 120 is present in component 102.

The component 100 includes an electronic shutter 105. The electronic shutter 105, which may sometimes be referred to as an intensity switch or an electrically tunable light modulator, may include a linear polarizer 108, a polarization switch 110, and a linear polarizer 112. The linear polarizer 108 may have a pass axis aligned with the Y-axis such that the light 104 is linearly polarized along the Y-axis after passing through the polarizer 108. The polarization switch 110, which may sometimes be referred to as an electrically adjustable wave plate, an electrically adjustable retarder, or an electrically adjustable polarization controller, may be formed from an electrically adjustable optical component such as a twisted nematic liquid crystal layer (as an example). The ac drive signal may be used to control the operation of the polarization switch 110 to avoid undesirable charge buildup effects that may otherwise result from the use of a control signal of a fixed polarity.

In a first state (sometimes referred to as an off state, where a 0V peak-to-peak drive signal is applied), polarization switch 110 rotates the polarization of incident linearly polarized light from polarizer 108 by 90 °, such that light 104 is polarized along the X-axis after exiting polarization switch 110. The linear polarizer 112 has a pass axis aligned with the X-axis and thus passes the light 104 in the first state. In a second state (sometimes referred to as an on state, where a 20V peak-to-peak drive signal or other suitable drive signal is applied), polarization switch 110 does not rotate the polarization of incident linearly polarized light. In this state, the light 104 is blocked by the polarizer 112. As this suggests, the adjustability of the polarization switch 110 allows the polarizer 108, the polarization switch 110, and the polarizer 112 to act as electrically adjustable shutters that can block or pass real world light 104 to the eye box 60.

The optical component 102 may include a linear polarizer 114. The linear polarizer 114 may have a pass axis aligned with the X-axis and may be used to block light polarized along the Y-axis, as described in connection with polarizer 112. The inclusion of polarizer 112 may help reduce display light leakage from output coupler 88 in the + Z direction. The polarizer 112 may be omitted, if desired. In a configuration in which the polarizer 112 is omitted, the polarizer 114, the polarizer 108, and the polarization switch 110 form an electronic shutter.

The optical component 102 may include a tunable lens, such as a liquid crystal lens. The position of the lens center of the tunable lens and/or the lens power of the lens may be adjusted by the control circuit 12. For example, the position of the lens center of the adjustable lens may be controlled in real-time based on information from a gaze tracking system that is monitoring the user's gaze direction (e.g., by monitoring the user's eyes in the eye box 60). This allows the center of the lens to be aligned along the user's line of sight.

In the example of fig. 3A, the component 102 includes a liquid crystal lens 118. The lens 118 is electrically adjustable. During operation, the control circuit 12 may adjust the power of the liquid crystal lens 118 to place the virtual object in a desired focal plane. By way of example, liquid crystal lens 118 may exhibit a positive lens power tunable between a first positive lens power value and a second positive lens power value, may exhibit a negative lens power tunable between a first negative lens power value and a second negative lens power value, or may have a lens power adjustable between a positive value (e.g., +1 diopter) and a negative value (e.g., -1 diopter). The net power of the lens system between the output coupler 88 and the eye box 60 is given by the combined lens power of the inner (rear) bias lens 120 and the liquid crystal lens 118. In some configurations, the inclusion of a negative rear-biased lens may help provide a desired overall negative lens power to a user (e.g., a lens power in a range from-0.5 diopters (which may be used to place a virtual object at a focal plane distance from eye box 602 m) to-2.5 diopters (which may be used to place a virtual object at a focal plane distance from eye box 6040 cm), while allowing lens 118 to exhibit both positive and negative lens powers, thereby helping to avoid tuning challenges that may sometimes exist when only a negative liquid crystal lens power is produced.lens 118 may be configured to exhibit a desired lens power for light polarized along the Y-axis (e.g., 1 diopter and/or other suitable lens powers), while not exhibiting a lens power (0) diopter for light polarized along the X-axis., one, two or more, three or more, etc.). If desired, a multi-layer configuration may be used for the lens 118 to allow the lens 118 to provide an electrically adjustable lens center position, to allow for enhanced optical performance of the lens 118, and the like.

Optical system 122 may use time division multiplexing to combine real world light 104 and display light 124 at eye box 60 for viewing by a user.

During a first time period (which may sometimes be referred to as a "world view off" period), the polarization switch 110 of the intensity switch 105 is adjusted to block the real world light 104. Display light 124 from output coupler 88 is linearly polarized along the X-axis by polarizer 114. The optical system 122 may have a polarization switch, such as polarization switch 116. The polarization switch 116 may be turned off whenever the polarization switch 110 is turned on and the intensity switch 105 blocks the real world image light 104. Because polarization switch 116 is off, polarization switch 116 rotates the polarization of display light 124 such that display light 124 is aligned along the Y-axis. The liquid crystal lens 118 is adjusted by the control circuit 12 to produce the desired lens power for light polarized along the Y-axis. The offset lens 120 provides additional desired lens power. The light 124 thus reaches the eye box 60 with the desired lens power interposed between the optical coupler 88 and the eye box 60. By adjusting the lens power (e.g., when control circuit 12 adjusts lens 118), while generating image frames synchronized with display 14 when intensity switch 105 is opaque and blocks real world light, virtual objects associated with respective frames of display image light 124 may be placed in one or more desired focal planes.

During a second time period (which may sometimes be referred to as a "world view on" period), the polarization switch 110 of the intensity switch 105 is adjusted to pass the real world light 104 while optionally turning off the display 14 (and not producing light 124). The polarization switch 116 is placed in a state that allows light to pass through the lens 118. During a second time period, the user views real world objects through the system 122. The liquid crystal lens 118 is sensitive only to light polarized along the Y-axis and is insensitive to light polarized along the X-axis. The light 104 is polarized along the X-axis when passing through the polarizer 114 and the polarization switch 116 may be turned on so the light 104 maintains its polarization state along the X-axis when passing through the lens 118 and is therefore unaffected by the lens 118. The combined optical powers of the anterior and posterior offset

lenses

106, 120 cancel out (in this example) such that there is no net lens power between the eye box 60 and the real world (i.e., the real world light 104 reaches the eye box 60 without being affected by the optical system 122). As shown in fig. 3B, the display 14 may be turned on or off when the real world light 104 passes through the system 122 during a second time period (the world view open period). The display 14 may be switched on or off, for example, depending on the depth of the virtual content to be displayed for the user in the eye-box 60. For example, if the virtual content to be placed at the focal plane corresponding to the lens 118 has zero power, the display 14 may be turned on.

During operation, control circuit 12 may operate polarization switches and other adjustable components synchronized by apparatus 10 (e.g., alternating between a world view on period and a world view off period). The relative duty cycle between the world view on and off states may be 50% (50% on and 50% off) or may have any other suitable value (e.g., 60% -70% on, less than 80% on, greater than 30% on, etc.). The world view may also be opened at a 100% duty cycle when there is no need to adjust the depth of the virtual content. In other words, in the configurations of fig. 3A and 3B, (and other configurations such as the configurations of fig. 6 and 9, if desired), the depth feature may be disabled when it is desired to increase the brightness of the world view.

Other polarization dependent lenses may be used for lens 118, if desired. For example, a geometric phase lens or a fixed birefringent lens may be used in place of the tunable lens 118. The fixed polarization dependent lens provides two different lens power options for the system 122 depending on the polarization state of the light passing through the lens. Eye tracking and lens center adjustment are not used in this configuration because the lens center position of the fixed lens is fixed.

Optical system 122 may use a complementary geometric phase lens pair if desired. The geometric phase lens may be implemented using a liquid crystal lens structure configured to exhibit positive lens power for one circular polarization, such as right-hand circular polarization (RCP), and negative lens power for the opposite circular polarization, such as left-hand circular polarization (LCP). Polarization control is used to avoid undesirable ghost images because both positive and negative lens power appear when presented with unpolarized light (containing equal portions of RCP and LCP light).

Fig. 4A shows an optical system based on geometric phase lenses GPL1 and GPL 2. The front and

rear biasing lenses

106, 120 are omitted from fig. 4A and subsequent figures to avoid unduly complicating the drawings.

As shown in fig. 4A, optical system 122 may have a quarter wave plate QWP2 between geometric phase lens GPL2 and polarization switch P2 (electrically adjustable polarization rotator). A linear polarizer LPOL is interposed between the waveguide 86 (output coupler 88) and the polarization switch P1. The quarter wave plate QWP1 is located between the polarization switch P1 and the lens GPL 1. In this configuration, the polarization switches P1 and P3 function as polarization rotators of linear polarization. In other configurations, the quarter wave plate QWP2 and the polarization switch P2 may be combined to form different types of polarization switches for circular polarization. Similarly, the quarter wave plate QWP1 and the polarization switch P1 may be combined to form a polarization switch for circularly polarized light. In other words, the quarter wave plates QWP1 and QWP2 may be omitted.

When the polarization switch P2 and the polarization switch P1 are off, the RCP real world light 104 is converted to LCP light by the lens GPL 2. The quarter wave plate QWP2 converts the LCP light into linearly polarized light along the Y axis. Polarization switch P2 is open, thus rotating the light so that it is polarized along the X-axis. The linear polarizer linear POL blocks the light. In this way, RCP real world light is prevented from reaching the user.

When the polarization switch P2 and the polarization switch P1 are off, the LCP real world light 104 is converted by the lens GPL2 to RCP light, which exhibits negative lens power. This light is converted to linearly polarized light that is polarized along the X-axis by the quarter wave plate QWP 2. Polarization switch P2 turns off and thus rotates the polarization of the light so that it is linearly polarized along the Y-axis. After passing through waveguide 86 (output coupler 88) and linear polarizer LPOL, the light reaches polarization switch P1. Polarization switch P1 switches off and thus rotates the polarization of light 104 such that the light exiting polarization switch P1 is polarized along the X-axis. The quarter wave plate QWP1 converts the linearly polarized light into RCP light. When the RCP light passes through the lens GP1, the lens GP1 exhibits a positive lens power equal and opposite to the lens GPL2, so the real world light 104 is not affected by any lens power (e.g., the lens power of the lenses GPL2 and GPL1 when combined is 0 diopters, so that the real world light 104 is viewable by the user as if the system 122 were not present).

When polarization switches P1 and P2 are on, LCP light 104 is blocked. The RCP light passes through a lens GPL2 that exhibits a positive lens power. The polarization switches P1 and P2 are turned on, and thus do not change the polarization state of light passing through them. After passing through the section between lenses GPL2 and GPL1, light 104 becomes left-handed circularly polarized. As shown in fig. 4A, when LCP light 104 reaches lens GPL1, lens GPL1 exhibits a negative lens power equal and opposite to the positive lens power of lens GPL 2. When both polarization switches P1 and P2 are off, the real world light 104 is not affected by the presence of lenses GPL1 and GPL2 when polarization switches P1 and P2 are on because the lens powers of lenses GPL1 and GPL2 cancel each other out.

In contrast, display light 124 is affected by the switching of polarization switches P1 and P2. When these switches are open, light 124 is RCP at the input of lens GPL1, which exhibits positive lens power. However, when polarization switches P1 and P2 are on, light 124 is LCP at the input of lens GPL1, such that lens GPL1 exhibits negative lens power.

During operation, the states of polarization switches P1 and P2 are adjusted in series (e.g., by alternating between on and off in synchronization with each other at a desired duty cycle). The real world light 104 is not affected by the state changes of the polarization switches P1 and P2, which allows the user to view the real world through the system 122 as if the system 122 were not present. Display light 124 experiences alternating lens powers due to its changing polarization state. When converted to RCP light, lens GPL1 applies positive lens power to display light 124, and when converted to LCP light, lens GPL1 applies negative lens power to display light 124. Thus, the system of FIG. 4A allows virtual objects (e.g., display image frames from display 14 properly synchronized with the switching of polarization switches 1 and 2) to be placed at two different focal planes. Systems such as the system of fig. 4A and others described herein may use a component stacking arrangement to achieve additional levels of focal plane positioning, if desired. Arrangements in which the optical system 122 exhibits first and second states having respective first and second focal plane positions for displaying a virtual object in an image are described herein as examples.

In the exemplary configuration of fig. 4B, the intensity switch 105 has a pair of linear polarizers LPOL and a switchable polarizer P2. A linear polarizer LPOL, a polarization switch P1 (for selecting the desired lens power for the geometric phase lens GPL), and a quarter wave plate QWP are located between the geometric phase lens GPL and the waveguide 86. With this configuration, the power of the offset lens may be configured such that when the positive power of the geometric phase lens GPL is selected, the display 14 may exhibit a slight negative power. In one example, the geometric phase lens GPL has a power of +/-1D, the negatively biased lens 120 has a power of-1.5D, and the positively biased lens 106 has a power of 0.5D. When positive power is selected for the geometric phase lens GPL, the display power will be + 1D-1.5D-0.5D, and the power applied to the real world light (sometimes referred to as world power) will be +0.5D + 1D-1.5D-0D. When negative power is selected, the display power will be-1D-1.5D ═ -2.5D.

In the exemplary configuration of fig. 5A, the optical system 122 has only a single polarization switch (switch P), and the position of the linear polarizer LPOL has been changed such that the linear polarizer LPOL is located between the polarization switch P and the eye box 60. There is also only a single Quarter Wave Plate (QWP) in the system 122 of fig. 5A. As shown in fig. 5A, the real world light 104 passes through the system 122 with 0 lens power regardless of whether the polarization switch P is on or off, because the positive power of the geometric phase lens GPL2 cancels the equal and opposite negative lens power of the geometric phase lens GPL1, while the display light 124 passes through the negative lens (GPL1) when the polarization switch P is off and through the positive lens (GPL1) when the polarization switch is on.

In the exemplary configuration of fig. 5B, a clean-up polarization switch formed by linear polarizer LPOL ', polarization switch P ', and quarter-wave plate QWP ' has been added to optical system 122 of fig. 5A to help block undesired ghost light, thereby improving the contrast ratio between the main image and the ghost image. The polarization switch P' may be operated in synchronization with the polarization switch P.

In the exemplary configuration of fig. 6, the system 122 has polarization switches PSA and PSB. The switch PSA may be used with a pair of linear polarizers LPOLX and LPOLY to achieve intensity switching. The switch PSB may be configured such that the RCP light passes through the switch PSB unaffected when the switch PSB is on, and may be configured such that the incoming RCP light is converted to LCP light when the switch PSB is off.

During operation in the "world view on" mode, display 14 is turned off, and switch PSA (and the electronic switch formed by polarizers LPOLX and LPOLY and polarization switch PSA) may be adjusted to pass light 104 through waveguide 86 and coupler 88. The LCP light is presented to lens GPL1, which exhibits negative lens power, and the RCP light is presented to lens GPL2, which exhibits an eliminating positive lens power.

During operation in the "world view off" mode, the display 14 is turned on and the switching PSA is adjusted to block real world light 104. Frames of image light (e.g., alternating first and second frames corresponding to alternating first and second virtual objects) are synchronized with the state of the polarization switch PSB. When the first frame is presented, switch PSB is on, and light 124 experiences negative lens power when passing through lens GPL1, and negative lens power when passing through lens GPL 2. When the second frame is presented, switch PSB is turned off, and light 124 experiences a negative lens power when passing through lens GPL1, and another negative lens power when passing through lens GPL 2. Thus, the first frame of display light experiences 0 lens power, and the second frame of display light experiences negative lens power (equal to the sum of the negative lens powers of lenses GPL1 and GPL 2). As with other systems shown in the figures, offset lenses, such as a front positive fixed offset lens and a complementary rear negative fixed offset lens, may be included in the system 122.

Another exemplary arrangement of optical system 122 is shown in fig. 7. When the polarization switch P is on, the real world light 104 experiences 0 lens power, and the RCP display light 124 experiences 0 lens power. LCP shows light blocked. When the polarization switch P is off, the real world light is blocked by the linear polarizer LPOL and the display light 124 experiences a negative lens power. The display 14 may be turned on and off according to the desired depth of content.

In the exemplary configuration of fig. 8, the display 14 supplies the waveguide 86 alternately with the RCP display light 124 or the LCP display light 124, and the waveguide 86 preserves the polarization state of the light from the display 14. The components of fig. 7, such as the quarter wave plate QWP, the linear polarizer LPOL, and the polarization switch P, may be omitted. Different virtual object positions are achieved by displaying content with different depths of different polarization (RCP for one depth and LCP for another depth).

Fig. 9 shows another exemplary configuration of the optical system 122. In the example of fig. 9, the geometric phase lens (GPL ') has been configured to pass 0-order light (light impinging on the lens GPL' at an angle parallel to the surface normal of the lens GPL ') at an intensity comparable to the intensity of the RCP and LCP output light from the lens GPL'. Thus, when the lens GPL' of fig. 9 presents unpolarized light (e.g., light having equal portions of LCP and RCP light), there will be three outputs: 1) LCP light (subject to negative lens power), 2) RCP light (subject to positive lens power), and 3)0 order light (subject to no lens power). The optical system 122 of figure 9 is configured to prevent LCP light from leaving the lens GPL'. When the display 14 is off, the polarization switch P2 (which forms an electronic shutter with linear polarizers LPOL-1 and LPOL-2) is configured to allow real-world light to pass to the polarization switch P1. The polarization switch P1 is open, which allows real world light to pass to the lens GPL' as RCP light. When the real world light 104 passes through the lens GPL ', the lens GPL' exhibits 0 lens power.

When the display 14 is on, the polarization switch P2 is adjusted so that the real world light 104 is blocked. The state of the polarization switch P1 alternates in synchronization with the image frames produced by the display 14 so that virtual objects may appear in different focal planes. When switch P1 is on, light 124 experiences negative lens power when passing through lens GPL ', and when switch P1 is off, light 124 experiences 0 lens power when passing through lens GPL'.

The system 8 may collect and use personally identifiable information. It is well known that the use of personally identifiable information should comply with privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining user privacy. In particular, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of authorized use should be explicitly stated to the user.

Physical environment

A physical environment refers to a physical world in which people can sense and/or interact without the aid of an electronic system. Physical environments such as physical parks include physical objects such as physical trees, physical buildings, and physical people. People can directly sense and/or interact with the physical environment, such as through vision, touch, hearing, taste, and smell.

Computer generated reality

In contrast, a computer-generated reality (CGR) environment refers to a fully or partially simulated environment in which people perceive and/or interact via electronic systems. In CGR, a subset of the human's physical movements, or a representation thereof, is tracked, and in response, one or more characteristics of one or more virtual objects simulated in the CGR environment are adjusted in a manner that complies with at least one laws of physics. For example, the CGR system may detect head rotations of a person and in response adjust the graphical content and sound field presented to the person in a manner similar to how such views and sounds change in the physical environment. In some cases (e.g., for accessibility reasons), adjustments to the characteristics of virtual objects in the CGR environment may be made in response to representations of physical motion (e.g., voice commands).

A person may utilize any of their senses to sense and/or interact with CGR objects, including vision, hearing, touch, taste, and smell. For example, a person may sense and/or interact with audio objects that create a 3D or spatial audio environment that provides a perception of a point audio source in 3D space. As another example, an audio object may enable audio transparency that selectively introduces ambient sound from a physical environment with or without computer-generated audio. In some CGR environments, a person may sense and/or interact only with audio objects.

Examples of CGR include virtual reality and mixed reality.

Virtual reality

A Virtual Reality (VR) environment refers to a simulated environment designed to be based entirely on computer-generated sensory input for one or more senses. The VR environment includes a plurality of virtual objects that a person can sense and/or interact with. For example, computer-generated images of trees, buildings, and avatars representing people are examples of virtual objects. A person may sense and/or interact with a virtual object in the VR environment through simulation of the presence of the person within the computer-generated environment and/or through simulation of a subset of the physical movements of the person within the computer-generated environment.

Mixed reality

In contrast to VR environments that are designed to be based entirely on computer-generated sensory inputs, a Mixed Reality (MR) environment refers to a simulated environment that is designed to introduce sensory inputs from a physical environment or representations thereof in addition to computer-generated sensory inputs (e.g., virtual objects). On a virtual continuum, a mixed reality environment is anything between the full physical environment as one end and the virtual reality environment as the other end, but not both ends.

In some MR environments, computer-generated sensory inputs may be responsive to changes in sensory inputs from the physical environment. Additionally, some electronic systems for presenting MR environments may track position and/or orientation relative to a physical environment to enable virtual objects to interact with real objects (i.e., physical objects or representations thereof from the physical environment). For example, the system may cause movement such that the virtual tree appears to be stationary relative to the physical ground.

Examples of mixed reality include augmented reality and augmented virtual.

Augmented reality

An Augmented Reality (AR) environment refers to a simulated environment in which one or more virtual objects are superimposed over a physical environment or representation thereof. For example, an electronic system for presenting an AR environment may have a transparent or translucent display through which a person may directly view the physical environment. The system may be configured to present the virtual object on a transparent or translucent display such that the human perceives the virtual object superimposed over the physical environment with the system. Alternatively, the system may have an opaque display and one or more imaging sensors that capture images or videos of the physical environment, which are representations of the physical environment. The system combines the image or video with the virtual object and presents the combination on the opaque display. A person utilizes the system to indirectly view the physical environment via an image or video of the physical environment and perceive a virtual object superimposed over the physical environment. As used herein, video of the physical environment displayed on the opaque display is referred to as "pass-through video," meaning that the system captures images of the physical environment using one or more image sensors and uses those images when rendering the AR environment on the opaque display. Further alternatively, the system may have a projection system that projects the virtual object into the physical environment, for example as a hologram or on a physical surface, so that a person perceives the virtual object superimposed on the physical environment with the system.

Augmented reality environments also refer to simulated environments in which representations of a physical environment are converted by computer-generated sensory information. For example, in providing a pass-through video, the system may transform one or more sensor images to apply a selected perspective (e.g., viewpoint) that is different from the perspective captured by the imaging sensor. As another example, a representation of a physical environment may be transformed by graphically modifying (e.g., magnifying) a portion thereof, such that the modified portion may be a representative but not real version of the original captured image. As another example, a representation of a physical environment may be transformed by graphically eliminating portions thereof or blurring portions thereof.

Enhanced virtualization

An enhanced virtual (AV) environment refers to a simulated environment in which a virtual or computer-generated environment incorporates one or more sensory inputs from a physical environment. The sensory input may be a representation of one or more characteristics of the physical environment. For example, an AV park may have virtual trees and virtual buildings, but the face of a person is realistically reproduced from an image taken of a physical person. As another example, the virtual object may take the shape or color of the physical object imaged by the one or more imaging sensors. As another example, the virtual object may employ a shadow that conforms to the positioning of the sun in the physical environment.

Hardware

There are many different types of electronic systems that enable a person to sense and/or interact with various CGR environments. Examples include head-mounted systems, projection-based systems, head-up displays (HUDs), display-integrated vehicle windshields, display-integrated windows, displays formed as lenses designed for placement on a person's eyes (e.g., similar to contact lenses), headphones/earphones, speaker arrays, input systems (e.g., wearable or handheld controllers with or without haptic feedback), smart phones, tablets, and desktop/laptop computers. The head-mounted system may have one or more speakers and an integrated opaque display. Alternatively, the head-mounted system may be configured to accept an external opaque display (e.g., a smartphone). The head-mounted system may incorporate one or more imaging sensors for capturing images or video of the physical environment, and/or one or more microphones for capturing audio of the physical environment. The head mounted system may have a transparent or translucent display instead of an opaque display. A transparent or translucent display may have a medium through which light representing an image is directed to a person's eye. The display may utilize digital light projection, OLED, LED, muled, liquid crystal on silicon, laser scanning light sources, or any combination of these technologies. The medium may be an optical waveguide, a holographic medium, an optical combiner, an optical reflector, or any combination thereof. In one embodiment, a transparent or translucent display may be configured to selectively become opaque. Projection-based systems may employ retinal projection techniques that project a graphical image onto a person's retina. The projection system may also be configured to project the virtual object into the physical environment, for example as a hologram or on a physical surface.

According to one embodiment, there is provided an electronic device including: a waveguide having an output coupler; a display configured to provide a display image to the waveguide, the display image being coupled out of the waveguide through the output coupler towards the eye-box; a polarization dependent lens through which a real world image or real world object is visible; an electronic shutter configured to switch between a transparent state in which the real world image passes through the electronic shutter and an opaque state in which the real world image is blocked by the electronic shutter; a polarization switch positioned between the output coupler and the tunable polarization dependent lens, the polarization switch configured to alternately switch between a first state when the electronic shutter is transparent, in which the polarization switch is configured to allow real world images to pass through the polarization dependent lens to the eye box without being focused by the polarization dependent lens, and a second state when the electronic shutter is opaque, in which the polarization switch is configured to allow display light to be focused by the polarization dependent lens while passing to the eye box.

According to another embodiment, the real world image has a first linear polarization when it reaches the polarization switch and the display image has a first linear polarization when it reaches the polarization switch, and the polarization switch is configured to pass the real world image through the polarization switch with the first linear polarization when the polarization switch is in the first state and to pass the display image through the polarization switch when the polarization switch is in the second state while rotating the polarization of the display image from the first linear polarization to a second polarization orthogonal to the first linear polarization.

According to another embodiment, the polarization dependent lens comprises a liquid crystal lens.

According to another embodiment, the polarization dependent lens comprises a liquid crystal lens configured to focus light having the second linear polarization and configured to unfocus light having the first linear polarization.

According to another embodiment, an electronic shutter includes an electrically adjustable liquid crystal layer.

According to another embodiment, an electronic shutter includes a first linear polarizer and a second linear polarizer.

According to another embodiment, the electrically adjustable liquid crystal layer is located between the first polarizer and the second polarizer.

According to another embodiment, an output coupler is located between the electrically adjustable liquid crystal layer and the second polarizer.

According to another embodiment, a second polarizer is positioned between the electrically adjustable liquid crystal layer and the output coupler.

According to another embodiment, the polarization dependent lens comprises a fixed birefringent lens that is not electrically adjustable.

According to another embodiment, the polarization dependent lens comprises an electrically adjustable lens.

According to another embodiment, an electronic device includes a positively biased lens and a negatively biased lens with an electronic shutter, an output coupler, a polarization switch, and a polarization dependent lens positioned between the positively biased lens and the negatively biased lens.

According to one embodiment, there is provided a head-mounted device comprising: a display configured to output a display image; a waveguide having an output coupler configured to transfer a display image from a display to an eye-box; a polarization dependent lens interposed between the output coupler and the eye box; a first polarization switch between the polarization dependent lens and the output coupler; and an electrically adjustable shutter having first and second linear polarizers and a second polarization switch between the first and second linear polarizers, the second polarization switch being switchable between a first state in which the electrically adjustable shutter blocks real world images from real world objects from reaching the polarization dependent lens and a second state in which the electrically adjustable shutter passes the real world images to the polarization dependent lens.

According to another embodiment, the first polarization switch is configured to switch between the first state and the second state in synchronization with the first state and the second state correspondence of the second polarization switch.

According to another embodiment, the display is configured to turn off the display image when the second polarization switch is in the second state and is configured to turn on the display image when the second polarization switch is in the first state.

According to another embodiment, the display image reaches the first polarization switch with a first linear polarization when the second polarization switch is in the first state, and the first polarization switch is configured to rotate the first linear polarization of the display image to a second linear polarization orthogonal to the first linear polarization when the first polarization switch is in the first state.

According to another embodiment, when the second polarization switch is in the second state, the real-world image arrives at the first polarization switch with a first linear polarization, and the first polarization switch is configured to pass the real-world image of the first linear polarization without rotating the first linear polarization of the real-world image.

According to one embodiment, there is provided a head mounted device comprising a display; a switchable optical component configured to switch synchronously between a first state and a second state; and a tunable liquid crystal lens through which a display image from the display is provided to the eye box during the first state but not the second state, and through which a real world image from the real world object is provided to the eye box during the second state but not the first state.

According to another embodiment, the switchable optical component comprises a first linear polarizer and a second linear polarizer, a first polarization switch between the first linear polarizer and the second linear polarizer, and a second polarization switch between the second linear polarizer and the tunable liquid crystal lens.

According to another embodiment, a head-mounted device includes a waveguide having an output coupler configured to pass a display image from a display to a second polarization switch.

According to another embodiment, the tunable liquid crystal lens has an electrically adjustable lens center position.

According to one embodiment, there is provided an electronic device including: a display configured to provide a display image; a waveguide having an output coupler through which a real world image from a real world object is viewable from the eyebox, the waveguide being configured to receive a display image from a display, and the output coupler being configured to couple the display image out of the waveguide toward the eyebox, and first and second geometric phase lenses each configured to exhibit a different lens power under different circular polarizations of light, the first geometric phase lens being positioned between the output coupler and the eyebox, and the output coupler being positioned between the second geometric phase lens and the first geometric phase lens.

According to another embodiment, an electronic device includes first and second polarization switches and a linear polarizer, an output coupler and a linear polarizer located between the first and second polarization switches, and a linear polarizer located between the output coupler and the first polarization switch.

According to another embodiment, the first and second polarization switches are configured to operate in a first state in which the display image passes through the first geometric phase lens with a first circular polarization and a second state in which the display image passes through the first geometric phase lens with a second circular polarization different from the first circular polarization.

According to another embodiment, the first geometric phase lens is configured to exhibit positive lens power for a display image passing through the first geometric phase lens with a first circular polarization.

According to another embodiment, the first geometric phase lens is configured to exhibit negative lens power for a display image passing through the first geometric phase lens with the second circular polarization.

According to another embodiment, the first geometric phase lens is configured to pass the real-world image to the eye box with a positive lens power when the first geometric phase lens receives the real-world image with the first circular polarization, and to pass the real-world image to the eye box with a negative lens power when the first geometric phase lens receives the real-world image with the second circular polarization.

According to another embodiment, the second geometric phase lens is configured to exhibit negative lens power for real world image light passing through the first geometric phase lens with positive lens power and positive lens power for real world image light passing through the first geometric phase lens with negative lens power.

According to another embodiment, an electronic device includes a first quarter wave plate between a first polarization switch and a first geometric phase lens, and a second quarter wave plate between a second geometric phase lens and a second polarization switch.

According to another embodiment, the first polarization switch includes a first electrically adjustable liquid crystal polarization rotator and the second polarization switch includes a second electrically adjustable liquid crystal polarization rotator.

According to another embodiment, an electronic device includes a polarization switch and a linear polarizer, the polarization switch is located between the first geometric phase lens and the linear polarizer, and the linear polarizer is located between the polarization switch and the eye-box.

According to another embodiment, an electronic device includes a quarter wave plate positioned between a first geometric phase lens and a polarization switch.

According to another embodiment, the polarization switch is configured to operate in a first state in which the display image passes through the first geometric phase lens with a first circular polarization and a second state in which the display image passes through the first geometric phase lens with a second circular polarization different from the first circular polarization.

According to another embodiment, the first geometric phase lens is configured to exhibit negative lens power for display images passing through the first geometric phase lens with a first circular polarization, and is configured to exhibit negative lens power for display images passing through the first geometric phase lens with a second circular polarization.

According to another embodiment, the first geometric phase lens is configured to pass the real-world image to the eye box with a negative lens power when the first geometric phase lens receives the real-world image with the first circular polarization, and to pass the real-world image to the eye box with a positive lens power when the first geometric phase lens receives the real-world image with the second circular polarization.

According to another embodiment, the second geometric phase lens is configured to exhibit positive lens power for real world image light passing through the first geometric phase lens with negative lens power and to exhibit negative lens power for real world image light passing through the first geometric phase lens with positive lens power.

According to one embodiment, there is provided an electronic device comprising a display configured to operate alternately in a first state and a second state, the display being configured to provide a display image when operating in the second state and not provide a display image when operating in the first state; a waveguide having an output coupler through which a real world image from a real world object is viewable from the eyebox, the waveguide being configured to receive a display image from a display, and the output coupler being configured to couple the display image out of the waveguide toward the eyebox, and first and second geometric phase lenses each configured to exhibit a different lens power under different circular polarizations of light, the first and second geometric phase lenses being positioned between the output coupler and the eyebox.

According to another embodiment, an electronic device includes a polarization switch positioned between the first geometric phase lens and the second geometric phase lens, the polarization switch configured to turn on during the second state.

According to another embodiment, an electronic device includes a linear polarizer located between an output coupler and a first geometric phase lens and a quarter wave plate located between the linear polarizer and the first geometric phase lens.

According to one embodiment, there is provided a head mounted device comprising a display configured to operate alternately in a first state and a second state, the display being configured to provide a display image of a first polarization state when operating in the first state and to provide a display image of a second polarization state different from the first polarization state when operating in the second state; a waveguide having an output coupler through which a real-world image from a real-world object is viewable from the eyebox, the waveguide being configured to receive a display image from a display, and the output coupler being configured to couple the display image out of the waveguide towards the eyebox; and a geometric phase lens interposed between the output coupler and the eye box, the geometric phase lens exhibiting positive lens power when the display image of the first polarization state passes through the geometric phase lens and exhibiting negative lens power when the display image of the second polarization state passes through the geometric phase lens.

According to another embodiment, the head-mounted device comprises a lens having a fixed negative lens power between the geometric phase lens and the eye box.

The foregoing is merely exemplary and various modifications may be made to the described embodiments. The foregoing embodiments may be implemented independently or in any combination.

Claims

1. An electronic device, the electronic device comprising:

a waveguide having an output coupler;

a display configured to provide a display image to the waveguide, the display image being coupled out of the waveguide through the output coupler towards an eye-box;

a polarization dependent lens through which a real world image or real world object is visible;

an electronic shutter, wherein the electronic shutter is configured to switch between a transparent state in which the real-world image passes through the electronic shutter and an opaque state in which the real-world image is blocked by the electronic shutter;

a polarization switch located between the output coupler and the tunable polarization dependent lens, wherein the polarization switch is configured to alternately switch between a first state when the electronic shutter is transparent and a second state when the electronic shutter is opaque,

wherein in the first state, the polarization switch is configured to allow the real-world image to pass through the polarization dependent lens to the eye box without being focused by the polarization dependent lens; and is

Wherein in the second state, the polarization switch is configured to allow the display light to be focused by the polarization dependent lens while passing to the eye box.

2. The electronic device of claim 1, wherein the real-world image has a first linear polarization upon reaching the polarization switch, and wherein the display image has the first linear polarization upon reaching the polarization switch, and wherein the polarization switch is configured to:

passing the real world image through the polarization switch with the first linear polarization when the polarization switch is in the first state; and is

When the polarization switch is in the second state, passing the display image through the polarization switch while rotating the polarization of the display image from the first linear polarization to a second polarization orthogonal to the first linear polarization.

3. The electronic device defined in claim 2 wherein the polarization-dependent lens comprises a liquid crystal lens.

4. The electronic device defined in claim 3 wherein the polarization-dependent lens comprises a liquid crystal lens that is configured to focus light having the second linear polarization and is configured to unfocus light having the first linear polarization.

5. The electronic device of claim 4, wherein the electronic shutter comprises an electrically adjustable liquid crystal layer.

6. The electronic device defined in claim 5 wherein the electronic shutter comprises a first linear polarizer and a second linear polarizer.

7. The electronic device of claim 6, wherein the electrically adjustable liquid crystal layer is located between the first polarizer and the second polarizer.

8. The electronic device defined in claim 7 wherein the output coupler is located between the electrically adjustable liquid crystal layer and the second polarizer.

9. The electronic device of claim 7, wherein the second polarizer is located between the electrically adjustable liquid crystal layer and the output coupler.

10. The electronic device defined in claim 1 wherein the polarization-dependent lens comprises a fixed birefringent lens that is not electrically adjustable.

11. The electronic device defined in claim 1 wherein the polarization-dependent lens comprises an electrically adjustable lens.

12. The electronic device defined in claim 1 further comprising positively and negatively biased lenses, wherein the electronic shutter, the output coupler, the polarization switch, and the polarization dependent lens are located between the positively and negatively biased lenses.

13. A head-mounted device, comprising:

a display configured to output a display image;

a waveguide having an output coupler configured to transfer the display image from the display to an eye box;

a polarization dependent lens interposed between the output coupler and the eye box;

a first polarization switch between the polarization dependent lens and the output coupler; and

an electrically adjustable shutter having a first linear polarizer and a second polarization switch between the first linear polarizer and the second linear polarizer, wherein the second polarization switch is switchable between a first state in which the electrically adjustable shutter blocks real world images from real world objects from reaching the polarization dependent lens and a second state in which the electrically adjustable shutter passes the real world images to the polarization dependent lens.

14. The headset device of claim 13, wherein the first polarization switch is configured to switch between a first state and a second state in synchronization with the first state and the second state correspondence of the second polarization switch.

15. The head mounted device of claim 14, wherein the display is configured to turn off the display image when the second polarization switch is in the second state and is configured to turn on the display image when the second polarization switch is in the first state.

16. The head-mounted device of claim 15, wherein the display image reaches the first polarization switch with a first linear polarization when the second polarization switch is in the first state, and wherein the first polarization switch is configured to rotate the first linear polarization of the display image to a second linear polarization orthogonal to the first linear polarization when the first polarization switch is in the first state.

17. The headset of claim 16, wherein the real-world image arrives at the first polarization switch with the first linear polarization when the second polarization switch is in the second state, and wherein the first polarization switch is configured to pass the real-world image with the first linear polarization without rotating the first linear polarization of the real-world image.

18. A head-mounted device, comprising:

a display;

a switchable optical component configured to switch synchronously between a first state and a second state; and

a tunable liquid crystal lens through which display images from the display are provided to an eye box during the first state but not the second state, and through which real world images from real world objects are provided to the eye box during the second state but not the first state.

19. The head-mounted device of claim 18, wherein the switchable optical component comprises:

a first linear polarizer and a second linear polarizer;

a first polarization switch located between the first linear polarizer and the second linear polarizer;

a second polarization switch located between the second linear polarizer and the tunable liquid crystal lens.

20. The head-mounted device of claim 19, further comprising:

a waveguide having an output coupler configured to pass the display image from the display to the second polarization switch.

21. The head mounted device of claim 18, wherein the tunable liquid crystal lens has an electrically adjustable lens center position.