Transmission improvement for flat lens based ar / vr glasses

Abstract

This application relates to a transmission improvement for AR / VR glasses based on flat lens, where an artificial reality display uses an anisotropic material to circularly polarize light out of a waveguide, making the artificial reality display relatively transparent. This application discloses a system comprising: a light source; a waveguide; a coupling element, wherein the coupling element is configured to couple light from the light source into the waveguide; a decoupling element, wherein: the decoupling element couples light out of the waveguide, and the light coupled out of the waveguide has a spatially varying polarization; a waveplate, wherein the waveplate has a spatially varying fast axis configured to convert the light having a spatially varying polarization into circularly polarized light; and a geometric phase lens configured to focus the circularly polarized light, wherein the waveplate is positioned between the decoupling element and the geometric phase lens.

Description

[0001] This application is a divisional application of the application filed on December 11, 2018, with application number 201880096715.8 and invention title "Improvement of Transmission for AR / VR Glasses Based on Planar Lenses". background

[0002] This disclosure generally relates to near-eye display systems, and more specifically to waveguide displays. Conventional near-eye displays typically have a display element that generates image light, which passes through one or more lenses before reaching the user's eyes. Furthermore, near-eye displays in virtual reality (VR) and / or augmented reality (AR) systems have compact, lightweight design standards and offer a two-dimensional extension with a large eyebox and a wide field of view (FOV). Traditionally, VR displays are magnifying optical displays. Computers generate images, and optics are used to magnify them. Designing near-eye displays to achieve a small form factor, large FOV, and / or large eyebox is a challenge. Overview

[0003] This disclosure relates to artificial reality displays. More specifically, but not limited to, using anisotropic materials to circularly polarize light departing from a waveguide, making the artificial reality display relatively transparent.

[0004] This application provides the following:

[0005] 1) A system comprising:

[0006] light source;

[0007] waveguide;

[0008] A coupling element, wherein the coupling element is configured to couple light from the light source into the waveguide;

[0009] A decoupling element, wherein the decoupling element is configured to couple light out of the waveguide such that the light decoupled from the waveguide has uniform polarization;

[0010] Waveplates, wherein the waveplates are configured to convert light with uniform polarization into circularly polarized light; and

[0011] A geometric phase lens configured to focus circular polarization, wherein the waveplate is located between the decoupling element and the geometric phase lens.

[0012] 2) According to the system described in 1), the uniform polarization is elliptic polarization.

[0013] 3) The system according to 1), wherein the light is polarized before entering the waveguide.

[0014] 4) According to the system described in 1), the geometric phase lens is a Pancharatnam Berry phase (PBP) liquid crystal lens.

[0015] 5) The system according to 1), wherein the waveplate has anisotropic material having uniform birefringence throughout the waveplate.

[0016] 6) The system according to 1), wherein the system includes a linear polarizer located between the light source and the coupling element.

[0017] 7) The system according to 1) further includes a framework, wherein:

[0018] The frame is part of the glasses worn by the user; and

[0019] The waveguide, the waveplate, and the geometric phase lens are fixed in the frame.

[0020] 8) The system according to 1), wherein the waveplate and the geometric phase lens are combined as part of a lens stack.

[0021] 9) The system according to 8), wherein:

[0022] The lens stack is a first lens stack;

[0023] The system also includes a second lens stack;

[0024] The second lens stack includes a geometric phase lens; and

[0025] The waveguide is located between the first lens stack and the second lens stack.

[0026] 10) A system comprising:

[0027] light source;

[0028] waveguide;

[0029] A coupling element, wherein the coupling element is configured to couple light from the light source into the waveguide;

[0030] Decoupling element, wherein:

[0031] The decoupling element couples light out of the waveguide; and

[0032] The light coupled out of the waveguide has spatially varying polarization;

[0033] A waveplate, wherein the waveplate has a spatially varying fast axis, the fast axis being configured to convert light with spatially varying polarization into circularly polarized light; and

[0034] A geometric phase lens configured to focus circular polarization, wherein the waveplate is located between the decoupling element and the geometric phase lens.

[0035] 11) The system according to 10), wherein:

[0036] The waveplate is divided into multiple regions;

[0037] The plurality of regions includes a first region and a second region; and

[0038] The waveplate comprises an optically anisotropic material having a fast axis of orientation variation, such that:

[0039] The fast axis in the first region is oriented at a first angle;

[0040] The fast axis in the second region is oriented at a second angle; and

[0041] The first angle is not equal to the second angle.

[0042] 12) According to the system of 11), wherein the plurality of regions produce a sub-threshold residual defocus of the combined light.

[0043] 13) According to the system described in 11), the number of the plurality of regions is equal to or greater than 25 and equal to or less than 225.

[0044] 14) The system according to 10) further includes a linear polarizer located between the light source and the coupling element.

[0045] 15) The system according to 10) further includes a framework, wherein:

[0046] The frame is part of the glasses worn by the user; and

[0047] The waveguide, the waveplate, and the geometric phase lens are fixed in the frame.

[0048] 16) A system comprising:

[0049] light source;

[0050] waveguide;

[0051] A coupling element, wherein the coupling element is configured to couple light from the light source into the waveguide;

[0052] A decoupling element, wherein the decoupling element is configured to couple light out of the waveguide;

[0053] A geometric phase lens, configured to focus circularly polarized light; and

[0054] A circular polarizer, comprising:

[0055] A linear polarizer with polarization bandwidth, wherein:

[0056] The polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and

[0057] The linear polarizer has a transmission axis; and

[0058] A waveplate, wherein the combination of the linear polarizer and the waveplate is configured to allow one type of circularly polarized light to pass through and block a second type of circularly polarized light.

[0059] 17) The system according to 16), wherein:

[0060] The linear polarizer is a first linear polarizer;

[0061] The polarization bandwidth is the first polarization bandwidth;

[0062] The system also includes a second linear polarizer;

[0063] The second linear polarizer has a second polarization bandwidth, wherein:

[0064] The second polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and

[0065] The second polarization bandwidth is different from the first polarization bandwidth.

[0066] 18) The system according to 17), wherein the first linear polarizer is configured to polarize red light and the second linear polarizer is configured to polarize blue light.

[0067] 19) According to the system described in 17), wherein:

[0068] The system also includes a third linear polarizer; and

[0069] The first linear polarizer, the second linear polarizer, and the third linear polarizer are part of the circular polarizer.

[0070] 20) The system according to 16), wherein the geometric phase lens is located between the decoupling element and the circular polarizer. Brief description of the attached diagram

[0071] The following illustrative embodiments are described with reference to the accompanying drawings.

[0072] Figure 1 This is a schematic diagram of an embodiment of a near-eye display.

[0073] Figure 2 This is an embodiment of a cross-section of a near-eye display.

[0074] Figure 3 An isometric view of an embodiment of a waveguide display is shown.

[0075] Figure 4 A cross-section of an embodiment of the waveguide display is shown.

[0076] Figure 5 This is a block diagram of an embodiment of a system including a near-eye display.

[0077] Figure 6 This is an exploded view of an embodiment of the lens system of a waveguide display component.

[0078] Figure 7 This is an exploded view of an embodiment of lens stacking in a lens system.

[0079] Figure 8 A cross-section of an embodiment of the waveguide is shown.

[0080] Figure 9 This shows the first example of the polarization of light leaving the waveguide.

[0081] Figure 10 An embodiment of fast-axis orientation of a lens with anisotropic material is shown.

[0082] Figure 11 This shows a second example of the polarization of light leaving the waveguide.

[0083] Figure 12 An embodiment of a fast-axis orientation of a lens with an anisotropic material having birefringent properties that vary in space is shown.

[0084] Figure 13 This is an exploded view of another embodiment of lens stacking.

[0085] Figure 14 An example of a flowchart illustrating the process of using a lens system is shown.

[0086] Figure 15 An embodiment of a process for manufacturing a lens with an anisotropic material having spatially varying birefringence is shown.

[0087] The accompanying drawings depict embodiments of the present disclosure for illustrative purposes only. Those skilled in the art will readily recognize from the following description that alternative embodiments of the illustrated structures and methods may be employed without departing from the principles and desirable benefits of this disclosure.

[0088] In the accompanying drawings, similar parts and / or features may have the same reference numerals. Furthermore, various parts of the same type can be distinguished by a dashed line following the reference numerals and a second reference numeral used to differentiate between similar parts. If only the first reference numerals are used in the specification, the description applies to any similar parts having the same first reference numerals, regardless of the second reference numerals. Detailed description

[0089] In the following description, specific details are set forth for purposes of explanation in order to provide a thorough understanding of certain inventive embodiments. However, it will be apparent that various embodiments may be practiced without these specific details. The accompanying drawings and description are not intended to be limiting.

[0090] This disclosure relates to reducing the hue of augmented reality (AR) displays and / or improving their efficiency. More specifically, but not limited thereto, this disclosure relates to reducing the hue of AR displays using Pancharatnam-Berry phase (PBP) lenses. U.S. Patent Application No. 15 / 693,846, filed September 1, 2017, uses PBP lenses to change the focal length of an AR display, which is incorporated by reference for all purposes. PBP lenses are specifically configured to receive circularly polarized light. Therefore, a circular polarizer can be placed in front of the PBP lens to provide circularly polarized light to the PBP lens. Conventional circular polarizers include a linear polarizer and a quarter-wave plate. The linear polarizer of a circular polarizer attenuates (e.g., reflects or absorbs) approximately half of randomly polarized light. Natural light is randomly polarized. Therefore, natural light is attenuated by approximately half by a lens system with a conventional circular polarizer, and the lens appears darker. In many cases, dark lenses may not be as socially acceptable as transparent glasses used for AR.

[0091] In AR displays, using a circular polarizer also reduces the efficiency of light from the projector. Waveguides can be used as pupil expanders in AR displays in various ways, such as pupil replication. Light is emitted from the projector, coupled into the waveguide, coupled out of the waveguide (e.g., using a grating), and transmitted to the user's eye. A PBP lens is placed between the waveguide and the user's eye to change the focal point of the light emitted from the waveguide, which allows for alteration of the waveguide's image plane. Placing a circular polarizer between the waveguide and the PBP lens reduces the transmission of displayed light because the linear polarizer in the circular polarizer attenuates light that is neither linearly polarized nor aligned with the transmission axis of the linear polarizer.

[0092] One way to reduce the attenuation of the linear polarizer in a circular polarizer is to remove the linear polarizer and design a grating to emit light with uniform polarization from the waveguide. Then, a waveplate can be used to change the uniformly polarized light emitted from the waveguide into circularly polarized light before the light is transmitted to the PBP lens.

[0093] Another method to reduce the attenuation of the linear polarizer in a circular polarizer is to linearly polarize the light coupled into the waveguide, but instead of designing the grating to output uniform polarization, a non-uniform waveplate is used to compensate for the non-uniform polarization leaving the waveguide. The light coupled from the waveguide can be non-uniformly polarized, but the non-uniformity can vary in a defined manner, allowing the non-uniform waveplate to be configured to convert the light from the waveguide into uniformly circularly polarized light. The non-uniformity and configuration of the waveplate depend on the defined manner in which the non-uniformly polarized light is coupled out of the waveguide. By determining the local variations in the polarization of the light emitted from the waveguide, the waveplate can be designed with local variations in the thickness of the birefringent material (e.g., liquid crystal) and / or the orientation of the optical axis to convert the light emitted from the waveguide into circularly polarized light without using a linear polarizer.

[0094] Another method to reduce attenuation is to use circular polarizers with limited bandwidth. In some embodiments, the projector uses a source with limited bandwidth. For example, the projector may have red, green, and blue light-emitting diodes (LEDs). Three circular polarizers may be placed between the waveguide and the PBP lens. The first circular polarizer may be a first linear polarizer with a limited bandwidth for polarizing red light corresponding to the wavelength of the red LED, the second circular polarizer may be a second linear polarizer with a limited bandwidth for polarizing green light corresponding to the wavelength of the green LED, and the third circular polarizer may be a third linear polarizer with a limited bandwidth for polarizing blue light corresponding to the wavelength of the blue LED. By polarizing only a portion of the visible spectrum, less natural light is attenuated by the linear polarizers.

[0095] Figure 1 This is a schematic diagram 100 of a near-eye display embodiment. The near-eye display 100 presents media to a user. Examples of media presented by the near-eye display 100 include one or more images, videos, and / or audio. In some embodiments, the audio is presented via an external device (e.g., a speaker and / or a headphone) that receives audio information from the near-eye display 100, a console, or both, and presents audio data based on the audio information. The near-eye display 100 is typically configured to operate as a virtual reality (VR) display. In some embodiments, the near-eye display 100 is modified to operate as an augmented reality (AR) display and / or a mixed reality (MR) display.

[0096] The near-eye display 100 includes a frame 105 and a display 110. The frame 105 is coupled to one or more optical elements. The display 110 is configured to allow a user to see content presented by the near-eye display 100. In some embodiments, the display 110 includes a waveguide display assembly for directing light from one or more images to the user's eye.

[0097] Figure 2 yes Figure 1 An embodiment of a cross-section 200 of a near-eye display 100 is shown. The display 110 includes at least one waveguide display component 210. The exit pupil 230 is the positioning of the eye 220 in the eyebox region when a user wears the near-eye display 100. For illustrative purposes, Figure 2 A cross section 200 is shown in association with eye 220 and waveguide display assembly 210; the second waveguide display assembly is for the user's second eye.

[0098] The waveguide display assembly 210 is configured to direct image light to the eye-friendly area located at the exit pupil 230 and to the eye 220. The waveguide display assembly 210 may be composed of one or more materials (e.g., plastic, glass, etc.) having one or more refractive indices. In some embodiments, the near-eye display 100 includes one or more optical elements between the waveguide display assembly 210 and the eye 220. In some embodiments, the waveguide display assembly 210 includes one or more waveguide displays to generate a single view to the user.

[0099] Figure 3 An isometric view of an embodiment of a waveguide display 300 is shown. In some embodiments, the waveguide display 300 is a component of the waveguide display assembly 210 of a near-eye display 100. In some embodiments, the waveguide display 300 is part of another near-eye display or other system that directs image light to a specific location.

[0100] The waveguide display 300 includes a source component 310, an output waveguide 320, and a controller 330. For illustrative purposes, Figure 3 A waveguide display 300 associated with a single eye 220 is shown, but in some embodiments, another waveguide display, separate or partially separate from the waveguide display 300, provides image light to the user's other eye.

[0101] Source component 310 generates image light 355. Source component 310 generates image light 355 and outputs it to coupling elements 350 located on a first side 370-1 of output waveguide 320. Output waveguide 320 is an optical waveguide that outputs extended image light 340 to the user's eye 220. Output waveguide 320 receives image light 355 at one or more coupling elements 350 located on the first side 370-1 and guides the received input image light 355. In some embodiments, coupling elements 350 couple image light 355 from source component 310 to output waveguide 320. Coupling elements 350 may be, for example, diffraction gratings, holographic gratings, one or more cascaded reflectors, one or more prism surface elements, superlenses, refractive surfaces with or without optical power at a certain angle, and / or arrays of holographic reflectors.

[0102] Light from output waveguide 320 is coupled out of output waveguide 320 using decoupling element 365. The extended image light 340, decoupled from output waveguide 320, is transmitted to the user's eye 220. In some embodiments, guiding element 360 is used to redirect light in output waveguide 320 to decoupling element 365. Guiding element 360 is part of or fixed to a first side 370-1 of output waveguide 320. Decoupling element 365 is part of or fixed to a second side 370-2 of output waveguide 320, such that guiding element 360 is opposite to decoupling element 365. Guiding element 360 and / or decoupling element 365 can be, for example, a diffraction grating, a holographic grating, one or more cascaded reflectors, one or more prism surface elements, Bragg gratings, and / or an array of holographic reflectors.

[0103] The second side 370-2 represents a plane along the x and y dimensions. The output waveguide 320 can be composed of one or more materials that facilitate total internal reflection of the image light 355 and have transparency in the wavelength band of interest. The output waveguide 320 can be composed of plastic, glass, and / or polymer. The output waveguide 320 has a relatively small form factor. For example, the output waveguide 320 can be approximately 50 mm wide along the x dimension; approximately 30 mm long along the y dimension; and approximately 0.3 to 5.0 mm thick along the z dimension.

[0104] In some embodiments, waveguide display 300 includes a plurality of output waveguides 320. For example, waveguide display 300 includes a stacked waveguide display. A stacked waveguide display is a multicolor display that can be projected onto multiple planes (e.g., a multi-plane color display; a red-green-blue (RGB) display generated by stacking output waveguides 320 for different colors). A stacked waveguide display may include three output waveguides 320, one output waveguide 320 for red light, one output waveguide 320 for green light, and one output waveguide 320 for blue light (sometimes referred to as waveguide stacking). In some configurations, a stacked waveguide display is a monochrome display that can be projected onto multiple planes (e.g., a multi-plane monochrome display). In some configurations, waveguide display 300 is a zoom waveguide display. A zoom waveguide display is a display that can adjust the focal position of image light emitted from a waveguide display. In some embodiments, waveguide display assembly 210 may include a stacked waveguide display and a zoom waveguide display. In some embodiments, a single output waveguide 320 is used for a wide spectrum. For example, a Bragg grating is used as a decoupling element 365 and couples red, green and blue light from the output waveguide 320.

[0105] The controller 330 controls the light emitted from the light source assembly 310. For example, the controller 330 controls the scanning operation of the source assembly 310 and / or the timing of the light source turning on and off. The controller 330 is capable of receiving scanning commands from the source assembly 310. The controller 330 can be used to control a full-field projector engine. In some embodiments, the output waveguide 320 outputs extended image light 340 with a large field of view (FOV) to the user's eyes 220. For example, providing extended image light 340 to the user allows the waveguide display 300 to have a field of view equal to or greater than 60 degrees and equal to or less than 150 degrees in the x and / or y directions. The output waveguide 320 is configured to provide an eye-friendly zone with a length equal to or greater than 10 mm and equal to or less than 50 mm in the x and / or y directions. The controller 330 can be used in conjunction with a graphics engine to render image information based on sensors measuring head and / or eye position.

[0106] Figure 4 An embodiment of a cross-section 400 of a waveguide display 300 is shown. Cross-section 400 includes a source component 310 and an output waveguide 320. The source component 310 generates image light 355 according to scanning instructions from a controller 330. The source component 310 includes a source 410 and an optical system 415. The source 410 is a light source that generates coherent light, partially coherent light, and / or incoherent light. The source 410 may include one or more of a laser diode, a vertical-cavity surface-emitting laser, a liquid crystal on silicon (LCD), an organic or inorganic light-emitting diode, and / or a superluminescent diode.

[0107] Optical system 415 includes one or more optical components that modulate light from source 410. Modulating light from source 410 may include, for example, expanding, collimating, and / or adjusting orientation according to instructions from controller 330. One or more optical elements in optical system 415 may be used for despeckling. Coherent light interference forms speckles. If all light is perfectly coherent and a plane wave, a macroscopic form of speckle is produced: interference fringes. Surface defects essentially create new light sources on optical elements that interfere at a microscopic level, producing speckles. Specks cannot be imaged away; instead, optical elements can be used to decoherentize coherent light or mix coherent light temporally or spatially. Spectral broadening, increasing and mixing angular range, depolarization, and temporal diffusion can help reduce speckle. Optical elements used for despeckling can be placed closer to the final image plane so that no new speckle sources appear. One or more optical components may include one or more lenses, liquid lenses, mirrors, free elements, apertures, metamaterials, and / or gratings. The light emitted from the optical system 415 (and the source component 310) is sometimes referred to as image light 355.

[0108] Output waveguide 320 receives image light 355. Coupling element 350 couples the image light 355 from source component 310 into output waveguide 320. In embodiments where coupling element 350 is a diffraction grating, the spacing of the diffraction grating is selected such that total internal reflection occurs in output waveguide 320, and image light 355 propagates internally in output waveguide 320 toward decoupling element 365 (e.g., by total internal reflection). Guiding element 360 redirects image light 355 to decoupling element 365 for decoupling from output waveguide 320.

[0109] In some embodiments, the guiding element 360 and / or decoupling element 365 are structurally similar. The extended image light 340 exiting the output waveguide 320 is extended along one or more dimensions (e.g., it may be stretched along the x-axis). In some embodiments, the waveguide display 300 includes a plurality of source components 310 and a plurality of output waveguides 320. Each source component 310 emits monochromatic image light corresponding to a specific band of a primary color (e.g., red, green, or blue). Each output waveguide 320 may be stacked together at intervals to output multicolor extended image light 340. In some embodiments, other color schemes (e.g., RGBW) are used.

[0110] Figure 5 This is a block diagram of an embodiment of a system 500 including a near-eye display 100. The system 500 includes a near-eye display 100, an imaging device 535, and an input / output interface 540, each coupled to a console 510.

[0111] The near-eye display 100 is a display that presents media to a user. Examples of media presented by the near-eye display 100 include one or more images, videos, and / or audio. In some embodiments, audio is presented via an external device (e.g., speakers and / or headphones) that receives audio information from the near-eye display 100 and / or console 510 and presents audio data to the user based on the audio information. In some embodiments, the near-eye display 100 may also function as AR glasses. In some embodiments, the near-eye display 100 utilizes computer-generated elements (e.g., images, videos, sounds, etc.) to enhance the view of the physical, real-world environment.

[0112] The near-eye display 100 includes a waveguide display assembly 210, one or more position sensors 525, and / or an inertial measurement unit (IMU) 530. The waveguide display assembly 210 includes a source assembly 310, an output waveguide 320, and a controller 330. The IMU 530 is an electronic device that generates rapid calibration data based on measurement signals received from one or more position sensors 525, indicating an estimated position of the near-eye display 100 relative to an initial position. An imaging device 535 generates slow calibration data based on calibration parameters received from a console 510. The imaging device 535 may include one or more cameras and / or one or more video cameras. An input / output interface 540 is a device that allows a user to send action requests to the console 510. An action request is a request to perform a specific action. For example, an action request could be to start or stop an application, or to perform a specific action within an application. The console 510 provides media to the near-eye display 100 for presentation to the user based on information received from one or more of the imaging device 535, the near-eye display 100, and the input / output interface 540. Figure 5 In the example shown, console 510 includes application storage 545, tracking module 550, and engine 555. Application storage 545 stores one or more applications for execution by console 510. An application is a set of instructions that, when executed by a processor, generates content to be presented to a user. Examples of applications include: game applications, conferencing applications, video playback applications, or other suitable applications. Tracking module 550 uses one or more calibration parameters to calibrate system 500, and one or more calibration parameters can be adjusted to reduce errors in determining the position of near-eye display 100. Tracking module 550 uses slow calibration information from imaging device 535 to track the movement of near-eye display 100. Tracking module 550 also uses position information from fast calibration information to determine the position of a reference point for near-eye display 100.

[0113] Engine 555 executes applications within system 500 and receives position information, acceleration information, velocity information, and / or predicted future position of near-eye display 100 from tracking module 550. In some embodiments, the information received by engine 555 may be used to generate a signal (e.g., a display instruction) to waveguide display component 210, which determines the type of content to be presented to the user.

[0114] Figure 6 This is an exploded view of an embodiment of the lens system of the waveguide display assembly 210. The lens system includes one or more waveguides 604 (e.g., similar to output waveguide 320) and one or more lens stacks 608. Figure 6 The lens system in the illustrated embodiment includes a first waveguide 604-1, a second waveguide 604-2, a third waveguide 604-3, a first lens stack 608-1, a second lens stack 608-2, and an adaptive dimming element 612. The lens system is fixed in a frame 105. Light from a light source 410 is coupled into the waveguide 604 using a coupling element 350. The light is guided in the waveguide 604 (e.g., using total internal reflection) and coupled out of the waveguide 604 using a decoupling element 365. The light coupled out of the waveguide 604 is directed to the user's eye 220 of the near-eye display 100. The waveguide 604 is part of the near-eye display 100.

[0115] Waveguide 604 and / or its decoupling element 365 can be constructed for specific optical wavelengths or frequency bands. For example, the decoupling element of the first waveguide 604-1 is designed to decouple red light; the decoupling element of the second waveguide 604-2 is designed to decouple green light; and the decoupling element of the third waveguide 604-3 is designed to decouple blue light. In some embodiments, the decoupling element of the first waveguide 604-1 is designed to decouple blue light; the decoupling element of the second waveguide 604-2 is designed to decouple green light; and the decoupling element of the third waveguide 604-3 is designed to decouple red light. In some embodiments, other color sequences of waveguide 604 are used and / or more than three or fewer waveguides 604 are used. In some embodiments, one waveguide 604 is used, and the decoupling element is configured to decouple red, green, and blue light.

[0116] A first lens stack 608-1 is positioned between waveguide 604 and the user's eye 220. Waveguide 604 is located between a second lens stack 608-2 and the first lens stack 608-1. In some embodiments, the second lens stack 608-2 is oriented perpendicular to the first lens stack 608-1. The second lens stack 608-2 may have elements similar to those of the first lens stack 608-1, arranged in a similar or different order; the second lens stack 608-2 may have elements different from those of the first lens stack 608-1. In some embodiments, the second lens stack 608-2 is not used. An adaptive dimming element 612 provides variable light attenuation (e.g., making the lens system darker for the user when the user is outdoors on a sunny day). The second lens stack 608-2 can be used to counteract the focusing capability of the first lens stack 608-1, so that even if the focus of light leaving waveguide 604 is altered by the first lens stack 608-1, natural light does not exhibit a change in focus. For example, the first lens stack 608-1 and the second lens stack 608-2 each have a Pancharatnam Berry phase (PBP) lens and a waveplate. Assuming that the amounts of right-handed and left-handed circularly polarized light are equal, light with random polarization from the real world passes through the PBP lens of the second stack 608-2, and half of the light is focused and half is defocused; when the light passes through the waveplate of the second lens stack 608-2, a delay is added on the axis; the light passes through waveguide 604, and the grating of waveguide 604 is not "seen" due to the angular selectivity of the grating; the light passes through the waveguide of the first lens stack 608-1, which eliminates the delay of the waveplate of the second lens stack 608-2; and the light passes through the PBP lens of the first lens stack 608-1, which defocuses and defocuses the PBP lens of the second lens stack 608-2.

[0117] Figure 7This is an exploded view of embodiment 700 of the first lens stack 608-1. The first lens stack 608-1 includes a waveplate 704, a first Pancharatnam Berry phase (PBP) lens 708-1, a switchable half-wave plate 712, and a second PBP lens 708-2. Notably, the linear polarizer is not located between the waveguide 604 and the PBP lens 708. U.S. Application No. 15 / 693,846, filed September 1, 2017, discloses a PBP lens for optical compensation. Application '846 is incorporated herein by reference for all purposes. The PBP lens 708 is a geometric phase lens and is specifically designed to receive circularly polarized light. A geometric phase lens can also be referred to as a planar lens. Planar lenses are based on metasurfaces, which can use nanostructures to modify polarization-based light. For example, a plane lens can focus light by acting as a converging lens for one rotational property of circularly polarized light (e.g., right-handed circularly polarized light) and a diverging lens for the orthogonal rotational property of circularly polarized light (e.g., left-handed circularly polarized light). In another example, a plane lens can reflect one rotational property of circularly polarized light and transmit the orthogonal rotational property of circularly polarized light. Geometric phase lenses may include liquid crystal polymers. In some embodiments, the elements of the lens stack 608 are combined together.

[0118] A circular polarizer can be placed in front of the PBP lens 708 to provide circularly polarized light to the PBP lens 708. For example, if a plane lens focuses right-handed circularly polarized light by converging the light rays, a right-handed circular polarizer can be placed in front of the PBP lens 708. However, a right-handed circular polarizer that includes a linear polarizer will attenuate the light passing through it, making the lens system appear darker because the linear polarizer attenuates light that is not linearly polarized and is oriented along the transmission axis of the linear polarizer. The circular polarizer also includes a quarter-wave plate. The quarter-wave plate can be made of a birefringent material with a fast axis and a slow axis. The fast axis of the quarter-wave plate is at 45 degrees to the transmission axis of the linear polarizer. Light passing through the linear polarizer will be polarized along the transmission axis and converted from linearly polarized light to circularly polarized light by passing through the quarter-wave plate. Because the linear polarizer of the circular polarizer attenuates randomly polarized light, the lens system will appear dark (e.g., like sunglasses). A dark lens system may not be as socially acceptable as a more transparent lens. Furthermore, due to the attenuation caused by the linear polarizer, having a linear polarizer between waveguides 604 in the PBP lens 708 may require the light source 410 to consume more power in order to transmit a brighter image to the user's eye 220.

[0119] A waveplate 704 is used in the absence of a linear polarizer between waveguide 604 and the PBP lens to generate circularly polarized light from the light coupled out of waveguide 604. Waveplate 704 is sometimes referred to as the first lens. Waveplate 704 is made of an optically anisotropic material. For example, waveplate 704 includes a birefringent material. PBP lens 708 and switchable half-wave plate 712 are used to change the focal length of the lens system (e.g., as described in '846 application). Waveplate 704 is configured to convert light coupled out of one or more waveguides 604 into circularly polarized light.

[0120] Figure 8 A cross-section of an embodiment of waveguide 604 is shown. Image light 355 is coupled into waveguide 604 via coupling element 350. The light is guided in waveguide 604 by total internal reflection. The light is coupled out of waveguide 604 by decoupling element 365 as extended image light 340. Image light 355 can be polarized (e.g., by placing a linear polarizer before coupling element 350 and / or by using a polarized light source, such as a laser diode, being p- or s-polarized). In some embodiments, waveguide 604, coupling element 350, and / or decoupling element 365 are designed to output polarized light (e.g., uniformly linearly polarized light or uniformly elliptically polarized light). For example, a surface relief grating or a liquid crystal Bragg grating can be used, as disclosed in Gregory P. Crawford, “Electrically Switchable Bragg Gratings,” Optics & Photonics News 14(4), 54-59 (2003), which is incorporated herein by reference. In some embodiments, the light coupled out of waveguide 604 has non-uniform polarization.

[0121] Figure 9A first example of the polarization of light exiting waveguide 604 is shown, where the extended image light 340 has uniform polarization. Light exiting waveguide 604 can have uniform polarization by designing a grating to decouple light with uniform polarization (e.g., as described in Gregory P. Crawford, “Electrically Switchable Bragg Gratings,” Optics & Photonics News 14(4), 54-59 (2003)). The polarization of the light coupled out of waveguide 604 (e.g., extended image light 340) is represented by a line labeled the polarization axis P. The polarization axis P is at an angle θ to the x-axis. The polarization axis P can represent the principal axis of linear polarization and / or elliptic polarization. Since the polarization of the extended image light 340 is uniform, the polarization is constant in x / y space, P(x, y) = θ (a constant). Waveplate 704 can be designed to convert the extended image light 340 into circularly polarized light (e.g., by making waveplate 704 a quarter-wave plate and orienting the fast axis of the quarter-wave plate at 45 degrees to θ, as described below).

[0122] Figure 10 An embodiment of a lens (e.g., waveplate 704) with an anisotropic material and fast axis F orientation is shown. The anisotropic material is birefringent (i.e., exhibiting two different refractive indices). The birefringent material has a fast axis F and a slow axis. The slow axis is typically orthogonal to the fast axis F, but not necessarily. The fast axis F of the waveplate 704 is designed to be at an angle φ to the polarization axis P, such that the extended image light 340 is converted into circularly polarized light. The fast axis F is at an angle β to the x-axis, such that β = θ + φ. If the polarization of the extended image light 340 is linear, then using a quarter-wave plate of the waveplate 704, φ can be equal to + / - 45°, depending on the desired directionality of circular polarization. For simplicity, this disclosure will provide examples using positive φ values, and it should be understood that negative φ values ​​can also be used. The angle φ is not necessarily 45°. To convert elliptically polarized light into circularly polarized light, the angle φ can be different from 45°, and / or the thickness of the waveplate 704 can be varied. For the uniform polarization of the extended image light 340, the fast axis F(x, y) = θ + φ (i.e., a constant). By using waveplate 704, there is no linear polarizer between waveguide 604 and waveplate 704. Compared to using a linear polarizer with waveplate 704, the light can be circularly polarized with less loss for PBP lens 708.

[0123] Figure 11A second example of the polarization of light exiting waveguide 604 is shown, where the extended image light 340 is spatially non-uniform. The polarization of the light can be altered within waveguide 604 (e.g., through reflection within the waveguide). Although the polarization of the light exiting waveguide 604 is non-uniform, it is deterministic. Generally, the polarization varies spatially and angularly with wavelength because the grating response is wavelength- and angle-dependent. Furthermore, the light path for each wavelength is slightly different within the waveguide. Since these variations are deterministic, spatially varying waveplates can be designed to compensate for the polarization variations. The waveplate can use multilayer birefringent films to produce an appropriate angular response.

[0124] The extended image light 340's x / y space is divided into m rows and n columns. Figure 11 In this system, m equals 2 and n equals 3, therefore there are six quadrants. Quadrants can be called regions. A region can be a closed two-dimensional shape (e.g., a rectangle, polygon, or free-form region). Figure 11 In the diagram, the regions are rectangular. In practice, the values ​​of m and n are typically greater than 2 or 3 (e.g., m and / or n are equal to or greater than 5, 7, or 10 and / or equal to or less than 12, 15, or 20). The polarization axes P in six different quadrants are shown. The first polarization axis P1 has an orientation of approximately θ = 130° in the first quadrant. The second polarization axis P-2 has an orientation of approximately θ = 95° in the second quadrant. The third polarization axis P-3 has an orientation of approximately θ = 20° in the third quadrant. The fourth polarization axis P-4 has an orientation of approximately θ = 70° in the fourth quadrant. The fifth polarization axis P-3 has an orientation of approximately θ = 40° in the fifth quadrant. The sixth polarization axis P-6 has an orientation of approximately θ = 160° in the sixth quadrant. Therefore, the angle θ is not a constant, but spatially correlated in the x and y directions, θ(x, y), and the polarization axes P are spatially correlated in the x and y directions, P(x, y) = θ(x, y). By employing birefringence that varies as a two-dimensional function of position on waveplate 704, a waveplate 704 can be created for spatially non-uniformly linearly polarized light to alter the extended image light 340. Therefore, a matching retarder (e.g., waveplate 704) can be partitioned relative to the waveguide polarization angle and / or ellipticity to produce substantially circular polarization within tolerances, such that the PBP lens focal position error is below a threshold that can be defined by wavefront error, point spread function error, or other image quality metrics. Multiple regions can be defined such that the residual defocus of the combined light is below a threshold.

[0125] Figure 12 An embodiment of waveplate 704 is shown, which is configured to reflect spatially non-uniform light (e.g., Figure 11The light described in the image is converted into circularly polarized light. Waveplate 704 has anisotropic material with spatially varying birefringence on the lens, such that the fast axis F of the birefringence is a function of x and y. Waveplate 704 is divided into m rows and n columns, similar to... Figure 11 The extended image light 340 is divided into x / y spaces, resulting in six quadrants. The fast axis F of the anisotropic material varies with x and y to match the polarization axis P (e.g., F(x, y) = P(x, y) + φ). In some embodiments, the angle φ also varies with x and y (e.g., quadrant two may be more linearly polarized than quadrant one, which is more elliptically polarized; therefore, the angle φ in quadrant two may differ from that in quadrant one). In an embodiment where the polarization of the extended image light 340 is linearly polarized and non-uniform, the first fast axis F-1 has an orientation of approximately β = 175° in the first quadrant; the second fast axis F-2 has an orientation of approximately β = 140° in the second quadrant; the third fast axis F-3 has an orientation of approximately β = 65° in the third quadrant; the fourth fast axis F-4 has an orientation of approximately β = 115° in the fourth quadrant; the fifth fast axis F-5 has an orientation of approximately β = 85° in the fifth quadrant; and the sixth fast axis F-6 has an orientation of approximately β = 205° in the sixth quadrant. Therefore, the orientation of the first fast axis F-1 in the first quadrant is a first angle, and the orientation of the second fast axis F-2 in the second quadrant is a second angle, wherein the first angle is not equal to the second angle.

[0126] Since the polarization of the light leaving waveguide 604 is definite, its polarization can be characterized. Waveplate 704 is constructed based on characterizing the polarization of the light coupled out of waveguide 604. For example, the output from waveguide 604 is divided into m×n regions (e.g., Figure 11 The spatial variation retarder (e.g., waveplate 704) is also constructed by dividing the spatial variation retarder into m×n regions. In some embodiments, m and / or n are equal to or greater than 7 and equal to or less than 100 (e.g., m = n = 5, 10, or 20). The fast axis F in each region is matched with the polarization P of the light in that region (and / or the thickness of the spatial variation retarder is matched) to convert the light emitted from waveguide 604 into circularly polarized light. By spatially matching the fast axis F with the polarization axis P in each region, waveplate 704 produces circularly polarized light for PBP lens 708 (sometimes referred to as the second lens) with less loss compared to a linear polarizer using waveplate 704. Therefore, no linear polarizer is used between waveguides 604 in PBP lens 708, and the lens system is more transparent than a lens system with a linear polarizer.

[0127] Figure 13This is an exploded view of another embodiment 1300 of the first lens stack 608-1. The first lens stack 608-1 in embodiment 1300 includes three circular polarizers 1304. The circular polarizers can be fabricated using linear polarizers and quarter-wave plates, wherein the transmission axis of the linear polarizer is offset by 45° from the fast axis of the quarter-wave plate. The circular polarizer 1304 includes a linear polarizer and a wave plate (e.g., a quarter-wave plate). The circular polarizer 1304 has a narrow bandwidth such that the linear polarizer of the circular polarizer 1304 polarizes light only within the narrow bandwidth. In some embodiments, the narrow bandwidth is equal to or greater than 5, 10, or 15 nm, and equal to or less than 20, 30, 35, 40, 50, 75, or 80 nm (e.g., the measured full width, half maximum). In some embodiments, the circular polarizer 1304 has narrow bandwidths centered on different wavelengths (e.g., filtering red, green, and blue light).

[0128] A first circular polarizer 1304-1 includes a first linear polarizer and a first waveplate. The first linear polarizer has a first polarization bandwidth; the first polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and the first linear polarizer has a first transmission axis. The first waveplate is configured to convert light polarized in the direction of the first transmission axis into circularly polarized light. A second circular polarizer 1304-2 includes a second linear polarizer and a second waveplate. The second linear polarizer has a second polarization bandwidth; the second polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and the second linear polarizer has a second transmission axis. The second waveplate is configured to convert light polarized in the direction of the second transmission axis into circularly polarized light. A third circular polarizer 1304-3 includes a third linear polarizer and a third waveplate. The third linear polarizer has a third polarization bandwidth; the third polarization bandwidth is equal to or greater than 5 nm and equal to or less than 50 nm; and the third linear polarizer has a third transmission axis. The third waveplate is configured to convert light polarized in the direction of the third transmission axis into circularly polarized light.

[0129] The first circular polarizer 1304-1 is used to polarize the red extended image light 340; the second circular polarizer 1304-2 is used to polarize the green extended image light 340; and the third circular polarizer 1304-3 is used to polarize the blue extended image light 340. Due to its narrow band, the circular polarizer 1304 attenuates less light than a broadband linear polarizer that is part of the circular polarizer, because only a portion of the ambient light is polarized by the linear polarizer of the circular polarizer 1304. Take the natural spectrum of 400 to 700 nm as an example; the spectrum of 300 nm. If a conventional linear polarizer is used, approximately half of the natural light will be absorbed (or reflected) by the conventional linear polarizer. However, if three circular polarizers 1304 are used, each with a polarization bandwidth of 30 nm, then only 90 nm of the natural light in the 300 nm spectrum will be polarized. Assuming a loss of 50% per wavelength and that the amplitude of the natural light is equal for each wavelength, then the loss is closer to 15% (e.g., 0.5 * 90 / 300), rather than closer to 50%. Therefore, by using a circular polarizer with a narrow bandwidth linear polarizer, natural light is reduced less, and the lens system appears more transparent.

[0130] In some embodiments, a single circular polarizer 1304 is used. For example, only red light can be used for source 410 (e.g., for a near-eye display for an aircraft pilot). In this case, the first circular polarizer 1304-1 is the only circular polarizer 1304 used, and not the second circular polarizer 1304-2 or the third circular polarizer 1304-3, to convert the red light into circularly polarized light. Similarly, if source 410 includes more than three colors, then more than three circular polarizers 1304 can be used.

[0131] The circular polarizer 1304 can be placed before (further from the eye than the PBP lens 708) or after (e.g., closer to the eye than the PBP lens 708) the PBP lens 708 ... Light from the real world passes through the PBP lens of the second lens stack 608-2 and is reversed by the PBP lens 708 of the first lens stack 608-1. The circular polarizer 1304 absorbs 50% of the light in this band.

[0132] In some embodiments, multiple (e.g., three) narrowband linear polarizers are used with a quarter-wave plate. Therefore, the circular polarizer 1304 may include three linear polarizers (e.g., one red, one green, and one blue) and only one quarter-wave plate. Some embodiments use only one quarter-wave plate because broadband achromatic quarter-wave plates are shared.

[0133] Figure 14 An embodiment of a flowchart of process 1400 using a lens system is shown. Process 1400 begins at step 1404, where light is emitted from a source (e.g., source 410). At step 1408, the light from the light source is coupled into a waveguide (e.g., waveguide 604) using a coupling element (e.g., coupling element 350). The light is guided through the waveguide to a decoupling element (e.g., decoupling element 365). At step 1412, the decoupling element is used to couple the light out of the waveguide and toward the user's eye (e.g., eye 220). In step 1416, the light is transmitted through a first lens (e.g., waveplate 704) to produce circularly polarized light. The first lens is made of an optically anisotropic material; the first lens does not include a polarizer; and the first lens is located between the decoupling element and the user's eye. At step 1418, the light is transmitted through a second lens, wherein the second lens is configured specifically to receive circularly polarized light (e.g., it is a PBP lens). The second lens is optically positioned between the first lens and the user's eye; and light is transmitted from the decoupling element to the second lens without passing through the polarizer.

[0134] Figure 15An embodiment of a flowchart for a process 1500 for producing a lens (e.g., waveplate 704) of an anisotropic material having spatially varying birefringence is shown. Process 1500 begins at step 1504, where light is emitted from a source (e.g., source 410). At step 1508, the light from the source is coupled into a waveguide (e.g., waveguide 604) using a coupling element (e.g., coupling element 350). The light is guided through the waveguide to a decoupling element (e.g., decoupling element 365). At step 1512, the decoupling element is used to couple the light out of the waveguide. At step 1516, the polarization of the light coupled out of the waveguide is analyzed. At step 1518, based on the analysis of the polarization of the light coupled out of the waveguide, the lens (e.g., waveplate 704) is designed to have positionally variable birefringence. In some embodiments, this is achieved by dividing the light into multiple regions (e.g., quadrants) and determining the polarization of the light in each region (e.g., as combined). Figure 11 (As discussed), to analyze the polarization of light coupled out of the waveguide.

[0135] Light from a light source (e.g., from light source assembly 310 and / or source 410) can be coupled into one or more waveguides 604 via one or more coupling elements (e.g., coupling element 350). The light from the light source can be polarized (e.g., emitted as polarized light or polarized before coupling element 350). The light can be linearly polarized or elliptically polarized. In some embodiments, the light from the light source is not polarized before being coupled into waveguide 604. In some embodiments, three waveguides 604 are used; one for red light, one for green light, and one for blue light. Light from waveguide 604 is coupled out of waveguide 604 via decoupling element 365. The decoupling element may include a grating.

[0136] In some embodiments, the grating is configured to couple light out of waveguide 604 such that the light is spatially uniformly polarized (e.g., as in combination with...). Figure 9 The discussion concerns linearly polarized or elliptically polarized light. Waveplates are designed to convert uniformly polarized light from a waveguide into circularly polarized light (e.g., as in combination with...). Figure 10 (As discussed). Circularly polarized light passes through the PBP lens and is focused by the PBP lens before reaching the user's eye 220 of the near-eye display 100.

[0137] In some embodiments, light is coupled out of waveguide 604 with deterministic and spatially varying polarization (e.g., as in combination with...). Figure 11 (As discussed). The light is non-uniformly polarized. Waveplates are designed to match the non-uniform polarization of light emitted from one or more waveguides 604 to convert the light into circularly polarized light (e.g., as in combination). Figure 12 (As described). Circularly polarized light passes through the PBP lens and is focused by the PBP lens before reaching the user's eye 220 of the near-eye display 100.

[0138] In some embodiments, one or more circular polarizers are used to circularly polarize light in a narrow band (e.g., 30 nm band); such as in combination Figure 13 (As discussed). The narrow band corresponds to the emission band of the light source (e.g., a light-emitting diode). Circularly polarized light passes through the PBP lens and is focused by the PBP lens before reaching the user's eye 220 of the near-eye display 100.

[0139] Embodiments of the present invention may be implemented using an artificial reality system or in combination with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some way before being presented to a user, and may include, for example, virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or some combination and / or derivative thereof. Artificial reality content may include fully generated content or generated content combined with captured (e.g., real-world) content. Artificial reality content may include video, audio, haptic feedback, or some combination thereof, and any of these may be presented in a single channel or in multiple channels (e.g., stereoscopic video that produces a three-dimensional effect for the viewer). Furthermore, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof for purposes such as creating content in artificial reality and / or being used in artificial reality in other ways (e.g., performing activities in artificial reality). Artificial reality systems that deliver artificial reality content can be implemented on a variety of platforms, including head-mounted displays (HMDs) connected to a host computer system, standalone HMDs, mobile devices or computing systems, or any other hardware platform capable of delivering artificial reality content to one or more viewers.

[0140] The foregoing description of embodiments of this disclosure is provided for illustrative purposes; it is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Those skilled in the art will recognize that many modifications and variations are possible in accordance with the above disclosure.

[0141] Some portions of this description describe embodiments of the present disclosure in terms of the algorithms and symbolic representations of operations on information. Those skilled in the art of data processing commonly use these algorithmic descriptions and representations to effectively communicate the substance of their work to others skilled in the art. While these operations are described functionally, computationally, or logically, they should be understood to be implemented by computer programs or equivalent circuits, microcode, etc. Furthermore, referring to these arrangements of operations as modules has sometimes proven convenient without loss of generality. The described operations and their associated modules can be embodied in software, firmware, and / or hardware.

[0142] The described steps, operations, or processes can be performed or implemented using one or more hardware or software modules, individually or in combination with other devices. In some embodiments, a software module is implemented using a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor to perform any or all of the described steps, operations, or processes.

[0143] Examples of this disclosure may also relate to means for performing the described operations. Such means may be specifically configured for the desired purpose, and / or may include a general-purpose computing device selectively activated or reconfigured by a computer program stored in a computer. Such a computer program may be stored in a non-transitory, tangible, computer-readable storage medium, or in any type of medium suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing system mentioned in the specification may include a single processor, or may be an architecture employing a multiprocessor design to enhance computing power.

[0144] Embodiments of this disclosure may also relate to products generated by the computational processes described herein. Such products may include information generated by the computational processes, wherein the information is stored on a non-transitory, tangible, computer-readable storage medium, and may include any embodiment of a computer program product or other combination of data described herein.

[0145] The language used in this specification has been chosen primarily for readability and instruction purposes, and may not have been chosen to depict or limit the inventive subject matter. Therefore, it is intended that the scope of this disclosure be limited not by this detailed description, but by any claims published on the application based thereon. Thus, the disclosure of embodiments is intended to be illustrative, not restrictive, of the scope of this disclosure, which is set forth in the appended claims.

Claims

1. An artificial reality display system, comprising: light source; waveguide; A coupling element, wherein the coupling element is configured to couple light from the light source into the waveguide; Decoupling element, wherein: The decoupling element couples light out of the waveguide; and The light coupled out of the waveguide has spatially varying polarization; A waveplate, wherein the waveplate has a spatially varying fast axis, the fast axis being configured to convert light with spatially varying polarization into circularly polarized light; and A geometric phase lens configured to focus circularly polarized light, wherein the waveplate is located between the decoupling element and the geometric phase lens.

2. The system according to claim 1, wherein: The waveplate is divided into multiple regions; The plurality of regions includes a first region and a second region; and The waveplate comprises an optically anisotropic material having a fast axis of orientation variation, such that: The fast axis in the first region is oriented at a first angle; The fast axis in the second region is oriented at a second angle; and The first angle is not equal to the second angle.

3. The system of claim 2, wherein the plurality of regions produce a sub-threshold residual defocus of the combined light.

4. The system according to claim 2, wherein the number of the plurality of regions is equal to or greater than 25 and equal to or less than 225.

5. The system of claim 1 further includes a linear polarizer located between the light source and the coupling element.

6. The system according to claim 1, further comprising a frame, wherein: The frame is part of the glasses worn by the user; and The waveguide, the waveplate, and the geometric phase lens are fixed in the frame.

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