TW202338411A - Phase plate and fabrication method for color-separated laser backlight in display systems - Google Patents

Abstract

According to examples, a method for phase plate fabrication may be described herein. The method may include providing an interferometer configuration to generate a hologram of a plurality of pinholes. In some examples, the interferometer configuration includes a substrate for photopolymer attachment, a photopolymer having a predetermined thickness, and an exposure mask with a plurality of pinholes. The method may also include exposing the photopolymer with collimated light, via a laser source, through the exposure mask with a plurality of pinholes, wherein the collimated light passes through the exposure mask itself to create a collimated beam, and the plurality of pinholes of the exposure mask to create a spherical wavefront. The collimated beam and the spherical wavefront may help generate the hologram on the photopolymer for use as a phase plate for improved light transmissivity in display systems.

Description

Phase plate and manufacturing method for color separation laser backlight in display system

This patent application relates generally to display systems, and more particularly to phase plates and manufacturing methods for dichroic laser backlights in display systems. Cross-references to related applications

This patent application claims the rights and interests of U.S. Provisional Patent Application No. 63/305,090 filed on January 31, 2022 and U.S. Non-Provisional Patent Application No. 18/100,698 filed on January 24, 2023. The disclosures of the above applications are incorporated herein by reference for all purposes.

With recent technological advancements, the popularity and proliferation of content creation and delivery has increased significantly in recent years. Specifically, interactive content, such as virtual reality (VR) content, augmented reality (AR) content, mixed reality (MR) content and real and/or virtual environments ( For example, content within and associated with the Metaverse has become attractive to consumers.

To facilitate the delivery of this and other related content, service providers have endeavored to offer various forms of wearable display systems. One such example may be a head-mounted device (HMD), such as a wearable headset, wearable goggles, or glasses. In some examples, a head mounted device (HMD) may employ a first projector and a second projector to direct light associated with the first image and the second image, respectively, through one or more respective lenses. The intermediate optical component is used to produce "binocular" or "stereoscopic" vision for the user to view. However, providing compact head-mounted devices (HMDs) with sufficiently bright and high-resolution images that are lightweight remains a constant challenge.

One aspect of the invention is a method for phase plate fabrication, which includes: providing an interferometer configuration to generate a plurality of pinhole holograms, wherein the interferometer configuration includes at least one photopolymer and an exposure mask; The photopolymer is exposed to the collimated light through the exposure mask having a plurality of pinholes by passing the collimated light through: the exposure mask for generating the collimated beam; and The plurality of pinholes used to generate a spherical wavefront, wherein the collimated beam and the spherical wavefront produce the hologram of the plurality of pinholes; pinhole placement is iteratively shifted for additional wavelengths so that the The photopolymer is repeatedly exposed to this collimated light.

In a method according to aspects of the invention, the interferometer configuration includes: a substrate for photopolymer attachment; the photopolymer having a predetermined thickness; and the exposure mask having the plurality of A pinhole.

In the method according to the aspect of the invention, the collimated light is laser light.

In the method according to the aspect of the invention, the plurality of pinholes in the exposure mask have a periodic structure.

In methods according to aspects of the invention, any two pinholes in the plurality of pinholes have a spacing of approximately 18 microns.

In a method according to aspects of the invention, each of the plurality of pinholes has a diameter of approximately 1 micron.

The method of this aspect of the invention further includes selecting to position the photopolymer between 100 microns and 200 microns from a Talbot self-imaging plane produced by the exposure mask.

The method according to the aspect of the invention further includes: adding a random phase to at least a portion of the plurality of pinholes in the exposure mask; or causing at least a portion of the pinholes in the exposure mask to Position randomization.

In a method according to aspects of the invention, the interferometer arrangement includes at least two exposure masks.

Another aspect of the invention is a method for configuring an exposure mask, which includes: determining the size of an exposure mask having a plurality of pinholes for phase plate fabrication; determining the size of the mask area relative to the pinholes The relative transmission of the holes; determining the size and position of the plurality of pinholes in the exposure mask based on the relative transmission; and manufacturing the exposure mask having the plurality of pinholes.

The method according to another aspect of the invention further includes determining the relative transmission using the following expression: Where T is the relative transmission between the exposure mask and the plurality of pinholes, p is the distance between each of the plurality of pinholes, and r is the radius of each pinhole.

In a method according to another aspect of the present invention, the plurality of pinholes in the exposure mask have a periodic structure.

In a method according to another aspect of the invention, any two pinholes in the plurality of pinholes have a spacing of about 18 microns.

In a method according to another aspect of the invention, each of the plurality of pinholes has a diameter of about 1 micron.

A method according to another aspect of the invention further includes adding a random phase to at least a portion of the plurality of pinholes in the exposure mask.

A method according to another aspect of the invention further includes randomizing the position of at least a portion of the pinholes in the exposure mask.

Yet another aspect of the invention is an interferometer arrangement for phase plate fabrication, the interferometer arrangement comprising: a substrate; a photopolymer having a predetermined thickness attached to the substrate; and an exposure mask having a plurality of pinholes to expose the photopolymer to collimated light by passing the collimated light through: the exposure mask for generating the collimated beam; and the plurality of pinholes for Generating a spherical wavefront, wherein the collimated beam and the spherical wavefront produce the hologram of the plurality of pinholes; iteratively shifting pinhole placement for additional wavelengths to repeatedly expose the photopolymer to the collimated Light.

In an interferometer configuration as described in yet another aspect of the invention, the photopolymer is repeatedly exposed to the collimated light by repeatedly shifting the pinhole placement for additional wavelengths.

In an interferometer configuration according to another aspect of the invention, the plurality of pinholes in the exposure mask have a periodic structure.

In an interferometer configuration according to yet another aspect of the invention, the photopolymer is placed between 100 microns and 200 microns away from the Talbot self-image plane created by the exposure mask.

For simplicity and illustrative purposes, the present application is described by referring primarily to its examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent that the present application may be practiced without these specific details. In other instances, some methods and structures that are easily understood by those with ordinary skill in the art are not described in detail to avoid unnecessarily confusing the present application. As used herein, the terms "a" and "an" are intended to designate at least one of a specific element, the term "includes" means including but not limited to, and the term "including" ” means including but not limited to, and the term “based on” means based at least in part.

Some display systems, such as VR-based head mounted devices (HMDs) and/or goggle devices, provide an immersive stereoscopic viewing experience. However, in some conventional displays, light transmission (or lack thereof) can be problematic. For example, in traditional liquid crystal displays (LCDs), such as those used in such VR-based HMDs, a large amount of light can be lost through the various optical layers that form the overall display. In many ways, this is called the "wall-plug efficiency" of LCDs. The systems and methods described herein may provide phase plate solutions and manufacturing methods for dichroic laser backlighting in display systems such as VR-based head-mounted devices (HMDs).

Figure 1 illustrates a block diagram of an artificial reality system environment 100 including a near-eye display, according to an example. As used herein, "near-eye display" may refer to a device (eg, an optical device) that may be in close proximity to a user's eyes. As used herein, "artificial reality" may refer to the "metaverse" or the appearance of environments with real and virtual components, etc., and may include those related to virtual reality (VR), augmented reality (AR), and/or Or the use of mixed reality (MR) related technologies. As used herein, "user" may refer to the user or wearer of the "near-eye display."

As shown in FIG. 1 , the artificial reality system environment 100 may include a near-eye display 120 , an optional external imaging device 150 , and an optional input/output interface 140 , each of which may be coupled to the console 110 . In some examples, the console 110 may be optional because the functionality of the console 110 may be integrated into the near-eye display 120 . In some examples, the near-eye display 120 may be a head-mounted display (HMD) that presents content to the user.

In some examples, for near-eye display systems, it may be generally desirable to expand the eye box, reduce display opacity, improve image quality (eg, resolution and contrast), reduce physical size, increase Power efficiency and increased or expanded field of view (FOV). As used herein, "field of view" (FOV) may refer to the angular range of an image as seen by a user, typically as viewed by one eye (for a monocular HMD) or both eyes (for a binocular HMD ) measured in units of observed degrees. Additionally, as used herein, an "eye movement zone" may be a two-dimensional window that may be placed in front of a user's eyes through which a displayed image from an image source may be viewed.

In some examples, in near-eye display systems, light from the surrounding environment can traverse a "see-through" region of the waveguide display (eg, a transparent substrate) to reach the user's eyes. For example, in a near-eye display system, light from a projected image can be coupled into a transparent substrate of a waveguide, propagate within the waveguide, and be coupled or directed out of the waveguide at one or more locations to replicate The ejection pupil expands the eye movement area.

In some examples, near-eye display 120 may include one or more rigid bodies that may be rigidly or non-rigidly coupled to each other. In some examples, rigid couplings between rigid bodies may cause the coupled rigid bodies to act as a single rigid entity, while in other examples, non-rigid couplings between rigid bodies may allow the rigid bodies to move relative to each other.

In some examples, near-eye display 120 may be implemented in any suitable form factor, including an HMD, a pair of glasses, or other similar wearable goggles or devices. Examples of the near-eye display 120 are further described below with respect to FIGS. 2 and 3 . Additionally, in some examples, the functionality described herein may be used in an HMD or head-mounted device that may combine images of the environment outside near-eye display 120 with artificial reality content (eg, computer-generated images). Therefore, in some examples, the near-eye display 120 may use generated and/or overlaid digital content (e.g., images, videos, sounds, etc.) to augment images of the physical, real-world environment outside the near-eye display 120 to provide users with Present augmented reality.

In some examples, near-eye display 120 may include any number of display electronics 122 , display optics 124 , and eye tracking units 130 . In some examples, the near-eye display 120 may also include one or more locators 126 , one or more position sensors 128 , and an inertial measurement unit (IMU) 132 . In some examples, near-eye display 120 may omit any of eye tracking unit 130 , one or more locators 126 , one or more position sensors 128 , and inertial measurement unit (IMU) 132 , or may include Additional components.

In some examples, display electronics 122 may display or facilitate the display of images to the user based on data received from, for example, optional console 110 . In some examples, display electronics 122 may include one or more display panels. In some examples, display electronics 122 may include any number of pixels to emit light in a primary color such as red, green, blue, white, or yellow. In some examples, the display electronics 122 may display a three-dimensional (3D) image using a stereoscopic effect produced by a two-dimensional panel to create a subjective perception of image depth.

In some examples, display optics 124 may display image content optically (eg, using optical waveguides and/or couplers), or amplify image light received from display electronics 122 and correct optical errors associated with the image light. , and/or present the corrected image light to the user of the near-eye display 120 . In some examples, display optics 124 may include a single optical element or any number of combinations of various optical elements and mechanical couplings to maintain relative spacing and orientation of the optical elements in the combination. In some examples, one or more optical elements in display optics 124 may have an optical coating, such as an anti-reflective coating, a reflective coating, a filter coating, and/or a combination of different optical coatings.

In some examples, display optics 124 may also be designed to correct for one or more types of optical errors, such as two-dimensional optical errors, three-dimensional optical errors, or any combination thereof. Examples of two-dimensional errors may include barrel distortion, pincushion distortion, longitudinal chromatic aberration, and/or lateral chromatic aberration. Examples of three-dimensional errors may include spherical aberration, chromatic aberration, field curvature, and astigmatism.

In some examples, one or more locators 126 may be objects that are located in a specific location relative to each other and relative to a reference point on the near-eye display 120 . In some examples, the optional console 110 can identify one or more locators 126 in images captured by the optional external imaging device 150 to determine the position and orientation of the artificial reality headset. Or both. One or more locators 126 may each be a light-emitting diode (LED), a corner reflector, a reflective marker, a type of light source that contrasts with the environment in which the near-eye display 120 operates, or any of these combination.

In some examples, external imaging device 150 may include one or more cameras, one or more video cameras, any other device capable of capturing images including one or more locators 126 , or any combination thereof. Optionally external imaging device 150 may be configured to detect light emitted or reflected from one or more locators 126 within the field of view of optional external imaging device 150 .

In some examples, one or more position sensors 128 may generate one or more measurement signals in response to movement of the near-eye display 120 . Examples of one or more position sensors 128 may include any number of accelerometers, gyroscopes, magnetometers, and/or other motion detection or error correction sensors or any combination thereof.

In some examples, inertial measurement unit (IMU) 132 may be an electronic device that generates fast calibration data based on measurement signals received from one or more position sensors 128 . One or more position sensors 128 may be external to the IMU 132 , internal to the IMU 132 , or any combination thereof. Based on one or more measurement signals from one or more position sensors 128 , the inertial measurement unit (IMU) 132 may generate fast calibration data that indicates the position of the near-eye display 120 relative to the initial position of the near-eye display 120 Estimated location. For example, the inertial measurement unit (IMU) 132 may integrate measurement signals received from the accelerometer over time to estimate a velocity vector, and integrate the velocity vector over time to determine a reference on the near-eye display 120 The estimated position of the point. Alternatively, the inertial measurement unit (IMU) 132 may provide sampled measurement signals to the optional console 110 so that quick calibration data may be determined.

Eye tracking unit 130 may include one or more eye tracking systems. As used herein, "eye tracking" may refer to determining the position or relative position of the eyes, including the orientation, position, and/or gaze of the user's eyes. In some examples, an eye tracking system can include an imaging system that captures one or more images of the eye, and optionally includes a light emitter that can generate light that is directed to the eye such that it is reflected by the eye. The light can be captured by the imaging system. In other examples, eye tracking unit 130 may capture reflected radio waves emitted by the micro radar unit. Such data associated with the eyes may be used to determine or predict eye position, orientation, movement, location and/or gaze.

In some examples, near-eye display 120 may use eye orientation to introduce depth cues (e.g., blurred images outside the user's primary line of sight) to gather insights about user interactions in virtual reality (VR) media (e.g., , time spent looking at any particular individual, object or frame as a function of the exposure stimulus), some other function based in part on the orientation of at least one of the user's eyes, or any combination thereof. In some examples, since the orientation can be determined for both eyes of the user, the eye tracking unit 130 may be able to determine where the user is looking or predict any user patterns, etc.

In some examples, input/output interface 140 may be a device that allows the user to send action requests to optional console 110 . As used herein, an "action request" may be a request to perform a specific action. For example, an action request may be to start or end an application or to perform a specific action within the application. Input/output interface 140 may include one or more input devices. Example input devices may include a keyboard, a mouse, a game controller, a glove, a button, a touch screen, or any other suitable device for receiving action requests and communicating the received action requests to the optional console 110 . In some examples, action requests received via input/output interface 140 may be communicated to optional console 110 so that actions corresponding to the requested actions may be performed.

In some examples, optional console 110 may provide content to near-eye display 120 for presentation based on information received from one or more of external imaging device 150 , near-eye display 120 , and input/output interface 140 user. For example, in the example shown in FIG. 1 , optional console 110 may include an app store 112 , a headset tracking module 114 , a virtual reality engine 116 , and an eye tracking module 118 . Some examples of optional consoles 110 may include different or additional modules than those described in conjunction with FIG. 1 . Functionality, described further below, may be distributed among the optional components of console 110 in a manner different from that described herein.

In some examples, the optional console 110 may include a processor and a non-transitory computer-readable storage medium that stores instructions executable by the processor. A processor may include multiple processing units that execute instructions in parallel. The non-transitory computer-readable storage medium can be any memory, such as a hard drive, removable memory, or a solid-state drive (e.g., flash memory or dynamic random access memory (DRAM) )). In some examples, modules of the optional console 110 described in conjunction with FIG. 1 may be encoded as instructions in a non-transitory computer-readable storage medium that, when executed by a processor, cause the processor to Perform the functions described further below. It should be understood that the optical console 110 may or may not be required, or the optional console 110 may be integrated with or separate from the near-eye display 120.

In some examples, application store 112 may store one or more applications for execution by optional console 110 . An application may include a set of instructions that, when executed by a processor, generate content for presentation to a user. Examples of applications may include: gaming applications, conferencing applications, video playback applications, or other suitable applications.

In some examples, headset tracking module 114 may use slow calibration information from external imaging device 150 to track movement of near-eye display 120 . For example, the headset tracking module 114 may use the observed localizer and the model of the near-eye display 120 from the slow calibration information to determine the location of the reference point of the near-eye display 120 . Additionally, in some examples, headset tracking module 114 may use portions of fast calibration information, slow calibration information, or any combination thereof, to predict the future position of near-eye display 120 . In some examples, headset tracking module 114 may provide the estimated or predicted future position of near-eye display 120 to virtual reality engine 116 .

In some examples, the virtual reality engine 116 can execute applications within the artificial reality system environment 100 and receive the position information of the near-eye display 120 , the acceleration information of the near-eye display 120 , and the near-eye display 120 from the headset tracking module 114 . Speed information, predicted future position of the near-eye display 120, or any combination thereof. In some examples, virtual reality engine 116 may also receive estimated eye position and orientation information from eye tracking module 118 . Based on the received information, the virtual reality engine 116 may determine content to provide to the near-eye display 120 for presentation to the user.

In some examples, the eye tracking module 118 may receive eye tracking data from the eye tracking unit 130 and determine the position of the user's eyes based on the eye tracking data. In some examples, the position of the eye may include the orientation, position, or both of the eye relative to near-eye display 120 or any components thereof. Therefore, in these examples, since the axis of rotation of the eye changes depending on the position of the eye in its eye socket, determining the position of the eye in its eye socket may allow the eye tracking module 118 to more accurately determine the orientation of the eye.

In some examples, the position of the display system's projector can be adjusted to implement any number of design modifications. For example, in some examples, the projector may be positioned in front of the viewer's eyes (ie, a "front-mounted" placement). In front-mounted installations, in some examples, the display system's projector may be positioned away from the user's eyes (i.e., "world side"). In some examples, a head-mounted display (HMD) device may utilize a front-mounted arrangement to direct light toward the user's eyes to project images.

2 illustrates a perspective view of a near-eye display in the form of a head-mounted display (HMD) device 200, according to an example. In some examples, HMD device 200 may be a virtual reality (VR) system, an augmented reality (AR) system, a mixed reality (MR) system, another system using a display or a wearable, or any combination thereof. part. In some examples, HMD device 200 may include a main body 220 and a head strap 230 . Figure 2 shows the bottom side 223, the front side 225 and the left side 227 of the body 220 in perspective view. In some examples, HMD device 200 may also include external cameras on the top/bottom/left/right/front exterior, such as lower right camera 228, upper left camera 229, and front camera 231, as shown. In some examples, head strap 230 may have an adjustable or extendable length. Specifically, in some examples, there may be sufficient space between the main body 220 of the HMD device 200 and the head strap 230 to allow the user to install the HMD device 200 on the user's head. In some examples, HMD device 200 may include additional, fewer, and/or different components.

In some examples, HMD device 200 may present media or other digital content to a user, including physical, virtual and/or augmented views of a real-world environment with computer-generated elements. Examples of media or digital content presented by HMD device 200 may include images (eg, two-dimensional; 2D) or three-dimensional (3D) images), video (eg, 2D or 3D video), audio, or any combination thereof . In some examples, images and videos may be presented to the user's eyes by one or more display assemblies (not shown in FIG. 2 ) enclosed in the body 220 of the HMD device 200 .

In some examples, the HMD device 200 may include various sensors (not shown), such as depth sensors, motion sensors, position sensors, and/or eye tracking sensors. Some of these sensors may use any number of structured or unstructured light patterns for sensing purposes. In some examples, HMD device 200 may include input/output interface 140 for communicating with console 110, as described with respect to FIG. 1 . In some examples, the HMD device 200 may include a virtual reality engine (not shown), but similar to the virtual reality engine 116 described with respect to FIG. 1 , which may execute applications within the HMD device 200 and select from various The sensor receives depth information, position information, acceleration information, speed information, predicted future position or any combination thereof of the HMD device 200 .

In some examples, information received by virtual reality engine 116 may be used to generate signals (eg, display commands) to one or more display assemblies. In some examples, the HMD device 200 may include locators (not shown), but similar to the virtual locators 126 described in FIG. 1 , the locators may be positioned on the HMD device 200 relative to each other and relative to a reference point. in a fixed position on the main body 220. Each of the locators can emit light detectable by an external imaging device. This may be suitable for head tracking or other movement/orientation purposes. It is understood that other elements or components may be used in addition to or in place of such locators.

It should be understood that in some examples, the projector installed in the display system may be positioned close to and/or closer to the user's eyes (ie, "eye side"). In some examples, and as discussed herein, a projector for a display system shaped like eyeglasses may be mounted or positioned in the temple (ie, the top far corner of the lens side) of the eyeglasses. It will be appreciated that in some instances, utilizing rear-mounted projector placement can help reduce the size or volume of any required housing required for the display system, which can also result in significantly improved user experience for the user.

As mentioned above, light transmittance (or lack thereof) can present problems in some display systems, such as VR-based head mounted devices (HMDs) and/or goggle devices. Low light transmittance limits brightness and minimizes the immersive visual experience desired by users. Therefore, the systems and methods described herein can help improve the "socket efficiency" of LCDs in such displays.

3A-3D illustrate cross-sectional views of a dichroic liquid crystal display (LCD) with a laser backlight, according to an example. Figure 3A illustrates the various layers forming LCD stack 300A. As shown, the LCD stack may include a white LED 302 backlight that transmits light via any number of optical components, such as a light guide plate (LGP) 303, one or more polarizers 312, 304, thin film transistors film transistor; TFT) 306, liquid crystal (liquid crystal; LC) layer 308, color filter (color filter; CF) 310, etc. As depicted, when light 314 passes through the LCD stack, each of these layers may reduce the amount of light passing through it in some manner, as indicated by a percentage. When calculated, the amount of light that is at least partially transmitted by the LCD stack including LGP, polarizer and TFT may actually be only a small fraction of the light at the end. By some estimates, the light transmittance can be approximately 0.0945 transmittance (9.45%) or less than 10%.

Accordingly, one of the primary goals of the systems and methods described herein is to improve light transmission in LCD stacks and provide increased brightness, vision, and higher quality images in AR/VR HMDs. One way to help minimize light loss may be to use alternative light sources or configurations.

3B illustrates a cross-sectional view of a dichroic liquid crystal display (LCD) with a laser backlight, according to an example. Here, instead of the white LED and LGP of FIG. 3A , the LCD stack 300B uses a laser backlight configuration including, for example, an RBG laser 322 , a light guide (LG) 323 and a micro lens array (MLS) 325 . In this example, the transmittance of light 324 for this portion of LCD stack 300B can be estimated to be only less than approximately 0.1575 (15.75%), or about 16%, which represents a significant improvement. 3C illustrates a close-up cross-sectional view of a dichroic liquid crystal display (LCD) 348 with a laser backlight using MLA, according to an example. Here, microlens array (MLA) 346 can focus beam 350 through the aperture, thereby enhancing overall transmission. Light from light source 342 may be provided to color selective microlens array (MLA) 346 via waveguide 344.

Additionally, FIG. 3D illustrates a cross-sectional view of a dichroic liquid crystal display (LCD) with a laser backlight using a phase plate according to another example. Here, instead of the microlens array (MLA) of FIG. 3B , the LCD stack 300D uses a laser backlight configuration including, for example, an RBG laser 322 , a grating light guide (LG) 323 and a phase plate 335 . With some calculations, the MLA in Figure 3B can have a transmittance of less than 50%, but the phase plate in Figure 3D can have a transmittance of greater than 60%. Therefore, the light transmittance of this portion of the LCD stack 300C using the phase plate can be estimated to be greater than 0.2268 (22.68%) or about 22%, which represents an even more significant improvement. In many ways, the use of a phase plate can also focus the beam through an aperture, thereby enhancing the overall transmission with even greater efficiency than an MLA layer.

In order for the phase plate to help provide improved transmission, there may be several parameters that optimize these results. 4A-4D illustrate cross-sectional pixel-level views of a dichroic liquid crystal display (LCD) with a laser backlight having a phase plate, according to an example. For example, diagram 400A in FIG. 4A shows source light 402 being adjusted by phase plate 404. As mentioned herein, phase plate 404 can change the relative phase of components of polarized light passing through the phase plate and also focus this light. Accordingly, the adjusted light 406 may be focused on the selected pixel 408 such that the blue light component is focused on the blue subpixel, the red light component is focused on the red subpixel, and the green light component is focused on the green subpixel. Here, there may be red, green, and blue pixels (eg, pixel 410) measuring approximately 18 micrometers (µm) in width (eg, in the range of 10 µm to 25 µm), with Each of the associated pores may be approximately 3.5 microns (eg, in the range of 2 µm to 5 µm). In order for this configuration to operate at high efficiency, it may be necessary for the light to pass through in a cone-like shape at approximately 40 degrees, as shown. Additionally, in some examples, the overall height can range from 200 µm to 500 µm. Using these parameters, an LCD with a laser backlight using a phase plate can provide design responses for the wavelengths associated with each of the three colors (red, green, and blue), such as having a pixel 422, a pixel substrate 405, and Phase plate 404 is shown in views 400B, 400C and 400D of Figures 4B, 4C and 4D.

Accordingly, the systems and methods described herein may provide phase plate manufacturing methods for dichroic laser backlights in display systems, such as VR-based head-mounted devices (HMDs). Specifically, the phase plate fabrication methods described herein can use an interferometer setup to create a hologram of a pinhole. The phase plate fabrication method described herein can also repeat the process any number of times with shifted pinholes for other wavelengths. The phase plate fabrication methods described herein can also play holograms with conjugate beams to produce desired illumination patterns. Various other examples may also be considered or provided.

Figure 5 illustrates an interferometer configuration 500 for generating a hologram of a pinhole for phase plate fabrication, according to an example. As shown, interferometer configuration 500 can include a substrate 510 to which photopolymer 508 can be attached. In some examples, photopolymer 508 may be 3 µm or greater (or typically <50 µm). Mask 504 with pinholes 506 may also be positioned at a distance of approximately 200 µm to 500 µm from photopolymer 508 . In this step of the phase plate manufacturing method, collimated laser light 507 may originate from the bottom of configuration 500 and pass through the 1% mask as a collimated beam. It should be understood that light can pass through the 1 µm pinhole 506 to create a spherical wavefront. In some examples, the collimated beam can interfere with a spherical wavefront at the photopolymer layer. This interference can help form the desired hologram pattern on the photopolymer used as a phase plate in a display as described above. It should be understood that a 1 µm pinhole can produce a 40° full width at half maximum (FWHM) cone angle: Sin (FFOV/2) = wavelength/pinhole diameter, (1) where FFOV means full view. field. Additionally, during this step, the exposure time can vary between 0.5 and 6 seconds depending on the laser power. In most cases, a 10mW/ ^cm2 laser can be used for approximately 1 second.

As mentioned above, this process can be repeated with shifted pinholes for other wavelengths. In some examples, configuration 500 may be used to expose different wavelength responses to different photopolymers, depending on thickness (eg, 3 µm to 50 µm) and photopolymer properties (eg, indexing dynamics). In other words, a red laser can be used for exposure, then the pinhole is shifted and a green laser is used, and then the pinhole is shifted again for a blue laser, and so on. Depending on how many exposures are performed, the thickness of the photopolymer can vary. For example, the more exposures to be performed, the thicker the photopolymer should be. This is usually due to the fact that the index dynamics of the material can usually be higher for thicker materials. One reason for extra exposure is capturing more than one wavelength, as described above. In the RBG example, the process involves multiplexing responses at three wavelengths. In some paradigms, it may be necessary to have off-axis exposure or other changes. In these situations, the process may involve additional beam steering, such as exposure at any number of different angles as well.

In some examples, more than one photopolymer layer may be provided. For example, three membranes can be used. For example, after exposing each of the films (red, green, and blue), each of the films can be laminated to each other using any number of lamination processes to also form a singular component .

6 illustrates a configuration 600 using a phase plate with a conjugate beam to produce an illumination pattern at a liquid crystal display (LCD) 608, according to an example. As shown, the phase plate formed from the above can be used in configuration 600. Specifically, configuration 600 may position the phase plate and hologram with conjugate beams to produce the desired illumination pattern for the LCD. Thus, RGB light 602 can pass through the transparent substrate, photopolymer 604 with pinholes, and arrive as modulated light 606 on a liquid crystal display (LCD) 608 . It should be understood that in some examples, the position between the phase plate and the TFT (eg, the first surface of the LCD) should be relatively the same as the exposure distance (200 µm to 500 µm), as shown in Figure 5. However, various other examples may also be considered or provided.

7A-7B illustrate views 700A-700B of an exposure mask for phase plate fabrication, according to an example. As described above, exposure mask 702 may include a plurality of pinholes 710, as shown in Figure 7A. In some examples, each of the pinholes may have a diameter 706 of approximately 1 μm. Patterning may also be present over the entire mask, and in some examples, pinholes 710 may be spaced apart by a distance 704 of 18 µm spacing. In some examples, the mask may also be coated with chrome, for example. Mask 702 may range in size from 5 x 5 cm to 8 x 8 cm, or any other relevant size or dimensions (see below for calculations). It should also be understood that the actual shape of pinhole 710 need not be completely circular. Slightly oval pinholes are also available. It should be understood that the pinholes can be configured to have 100% light transmission, while the chrome (other parts) of the mask can be configured to have 0.4% light transmission. That is, in actual operation, the hole transmission is likely to be less than 100%, and therefore the chromium transmission can be scaled accordingly.

Figure 7B illustrates a potential calculation 700B for exposure mask size according to an example. As shown, for a given mask with a pinhole of radius r (1/2 the pinhole diameter 706 ) and a distance 704 between pinholes p = 18 µm, the following expression can be used to calculate: (2) where T is the relative transmission of the masked area (black) relative to the pinhole (white), and arcsin (λ/2r) = 20° results in 2r = 1.3 µm with a 20° angle for 450 nm. Other calculations are available as shown. Ultimately, these calculations can be used to maximize edge contrast for interference exposures with approximately the same light/area between collimated and spherical wavefronts.

It should be understood that the above process can experience what may be called the "Talbot image plane" problem. In short, when collimated light passes through a periodic pinhole structure, a phenomenon called the "Talbot self-image plane" can occur at some distance away from the pinhole mask. In other words, when a plane wave is incident on a periodic diffraction grating, the image of the grating can be repeated at regular distances away from the grating plane. In this context, the regular distance can be called the Talbot length, and the repeated image can be called a "self-image" or a "Talbot image."

In order to prevent the reference beam from interfering with the Talbot plane (replication of the pinhole), the systems and methods described in this article can provide at least one of the following solutions: (1) Shift the interference plane away from the Talbot plane 100 µm to 200 µm (e.g., Talbot plane at 500 µm, then place photopolymer at 600 µm to 700 µm); (2) add random phase to the pinhole to destroy the periodic phase; (3) Randomize the 1 µm pinhole locations by a double µm offset to avoid periodic patterns; and/or (4) Use two or more of the masks, where each mask increases the change in Talbot The period of distance.

In addition to the methods, processes, and/or techniques described above, there may be any number of ways to generate phase masks for use in phase plate solutions for improved light transmission in display systems. These may include photolithography (binary or grayscale), nanoimprinting, ultra- or nanostructures (eg, nanopillars) or other similar methods, processes and/or technologies. Depending on cost, speed, and ease of use, these and/or other methods, processes, and/or techniques may be incorporated into the systems and methods described herein.

In the foregoing description, various inventive examples are described, including devices, systems, methods, and the like. For purposes of explanation, specific details are set forth in order to provide a thorough understanding of the disclosed examples. However, it is understood that various examples may be practiced without such specific details. For example, devices, systems, structures, assemblies, methods, and other components may be shown as components in block diagram form so as not to obscure the examples with unnecessary detail. In other instances, well-known devices, processes, systems, structures, and techniques may be shown without necessary detail to avoid obscuring the examples.

The drawings and descriptions are not intended to be limiting. The terms and expressions have been used in this disclosure as terms of description and not of limitation, and the use of such terms and expressions is not intended to exclude any equivalents of the features shown and described, or portions thereof. The word "example" is used herein to mean "serving as an example, example, or illustration." Any specific example or design described herein as an "example" is not necessarily to be construed as being better or superior to other specific examples or designs.

Although the methods and systems as described herein may be primarily targeted at digital content (such as video or interactive media), it is understood that the methods and systems as described herein may also be used with other types of content or contexts. Other applications or uses of methods and systems as described herein may also include social network connectivity, marketing, content-based recommendation engines, and/or other types of knowledge or data-driven systems.

100: Artificial reality system environment 110:Console 112: App Store 114:Head mounted device tracking module 116:Virtual Reality Engine 118: Eye tracking module 120: Near-eye display 122: Display electronics 124: Display optics 126:Locator 128: Position sensor 130: Eye tracking unit 132:Inertial measurement unit 140:Input/output interface 150:External imaging device 200:Head mounted display device 220:Subject 223: Bottom side 225:Front side 227:Left 228:Lower right camera 229:Upper left camera 230:Head strap 231:Front camera 300A: LCD stack 300B:LCD stack 300C: LCD stack 300D: LCD stack 302:White LED 303:Light guide plate 304:Polarizer 306:Thin film transistor 308: Liquid crystal layer 310: Color filter 312:Polarizer 314:Light 322:RBG laser 323:Grating light guide 324:Light 325:Microlens array 335: Phase plate 342:Light source 344:Waveguide 346:Microlens array 348: Color separation LCD display 350:Beam 400A: Schema 400B:View 400C:View 400D:View 402:Source light 404: Phase plate 405: Pixel substrate 406:Light 408:pixel 410: pixels 422: pixels 500:Interferometer configuration 502: Source light 504: Mask 506: Pinhole 507:Collimated laser light 508:Photopolymer 510:Substrate 600:Configuration 602:RGB light 604:Photopolymer 606: Adjusted light 608:LCD display 700A:View 700B:View 702: Exposure mask 704:Distance 706:Diameter 710: Pinhole r:radius

Features of the present disclosure are illustrated by means of examples and are not limited to the following drawings in which like numerals refer to like elements. Those of ordinary skill in the art will readily recognize from the following that alternative examples of the structures and methods illustrated in the figures may be employed without departing from the principles described herein. [Figure 1] A block diagram illustrating an artificial reality system environment including a near-eye display according to an example. [Fig. 2] A perspective view illustrating a near-eye display in the form of a head-mounted display (HMD) device according to an example. [FIG. 3A] to [FIG. 3D] illustrate cross-sectional views of a dichroic liquid crystal display (LCD) with laser backlight according to an example. [FIG. 4A] to [FIG. 4D] illustrate cross-sectional pixel-level views of a dichroic liquid crystal display (LCD) with a laser backlight having a phase plate, according to an example. [FIG. 5] illustrates an interferometer configuration for generating a hologram of a pinhole for phase plate fabrication, according to an example. [FIG. 6] illustrates a configuration using a phase plate with a conjugate beam to generate an illumination pattern at a liquid crystal display (LCD) according to an example. [FIG. 7A] to [FIG. 7B] illustrate views of an exposure mask used for phase plate manufacturing according to an example.

500:Interferometer configuration

502: Source light

504: Mask

506: Pinhole

507:Collimated laser light

508:Photopolymer

510:Substrate

Claims (20)

A method for phase plate manufacturing, which includes: An interferometer configuration is provided to generate a hologram of a plurality of pinholes, wherein the interferometer configuration includes at least one photopolymer and an exposure mask; The photopolymer is exposed to the collimated light through the exposure mask having a plurality of pinholes by passing the collimated light through: the exposure mask used to produce a collimated light beam; and the plurality of pinholes for generating a spherical wavefront, wherein the collimated beam and the spherical wavefront generate the hologram of the plurality of pinholes; and The photopolymer is repeatedly exposed to the collimated light by repeatedly shifting the pinhole placement for additional wavelengths. Such as the method of claim 1, wherein the interferometer configuration includes: a substrate for photopolymer attachment; The photopolymer has a predetermined thickness; and The exposure mask has the plurality of pinholes. The method of claim 1, wherein the collimated light is laser light. The method of claim 1, wherein the plurality of pinholes in the exposure mask have a periodic structure. The method of claim 4, wherein any two pinholes in the plurality of pinholes have a spacing of about 18 microns. The method of claim 1, wherein each of the plurality of pinholes has a diameter of about 1 micron. For example, the method of request item 1 further includes: The photopolymer was selected to be placed between 100 microns and 200 microns from the Talbot self-image plane produced by the exposure mask. For example, the method of request item 7 further includes: Add a random phase to at least a portion of the plurality of pinholes in the exposure mask; or The position of at least a portion of the pinholes in the exposure mask is randomized. The method of claim 1, wherein the interferometer configuration includes at least two exposure masks. A method for configuring an exposure mask, which includes: Determine the size of an exposure mask with multiple pinholes for phase plate manufacturing; Determine the relative transmission of the mask area relative to the pinhole; Determine the size and location of the plurality of pinholes in the exposure mask based on the relative transmission; and The exposure mask having the plurality of pinholes is manufactured. The method of claim 10, further comprising: determining the relative transmission using the following expression: Where T is the relative transmission between the exposure mask and the plurality of pinholes, p is the distance between each of the plurality of pinholes, and r is the radius of each pinhole. The method of claim 10, wherein the plurality of pinholes in the exposure mask have a periodic structure. The method of claim 12, wherein any two pinholes in the plurality of pinholes have a spacing of about 18 microns. The method of claim 10, wherein each of the plurality of pinholes has a diameter of approximately 1 micron. For example, the method of request item 10 further includes: A random phase is added to at least a portion of the plurality of pinholes in the exposure mask. For example, the method of request item 10 further includes: The position of at least a portion of the pinholes in the exposure mask is randomized. An interferometer configuration for phase plate manufacturing, the interferometer configuration includes: substrate; A photopolymer having a predetermined thickness attached to the substrate; and An exposure mask having a plurality of pinholes for exposing the photopolymer to collimated light by passing the collimated light through: the exposure mask used to produce a collimated light beam; and The plurality of pinholes are used to generate a spherical wavefront, wherein the collimated beam and the spherical wavefront generate the hologram of the plurality of pinholes; The photopolymer is repeatedly exposed to the collimated light by repeatedly shifting the pinhole placement for additional wavelengths. The interferometer configuration of claim 17, wherein the pinhole placement is iteratively shifted for additional wavelengths to repeatedly expose the photopolymer to the collimated light. The interferometer configuration of claim 17, wherein the plurality of pinholes in the exposure mask have a periodic structure. The interferometer configuration of claim 17, wherein the photopolymer is positioned between 100 microns and 200 microns from the Talbot self-image plane produced by the exposure mask.