Device having optical layer for collimating light beams and screen door effect mitigation and methods for adapting the same

Abstract

In accordance with an embodiment, a device includes an optical layer (610) configured to be disposed over a subpixel of a plurality of subpixels (614), each subpixel of the plurality of subpixels emitting a beam and corresponding to a color. In addition, the device may include the optical layer that is configured to combine the beams of each subpixel of the plurality of subpixels and / or to mix the colors of the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch. The device may include embodiments where a divergence solid angle of the combined beams overlaps at least 80 percent of a divergence solid angle of each subpixel of the plurality of subpixels.

Description

DEVICE HAVING OPTICAL LAYER FOR COLLIMATING LIGHT BEAMS AND SCREEN DOOR EFFECT MITIGATION AND METHODS FOR ADAPTING THE SAMEPRIORITY CLAIM AND CROSS-REFERENCE

[0001] This patent application claims priority to U.S. Provisional Application No. 63 / 611,632, filed on December 18, 2023 and entitled “RGB all-color display consolidator for both efficient light collection and mitigate screen door effect,” which is hereby incorporated by reference herein as if reproduced in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to display devices, and in particular embodiments, to display devices having optical layers to mitigate the screen door effect and improve optical efficiency by collimating the light beams to collect more light by image optics, and methods for adapting the same.BACKGROUND

[0003] In the field of optics, etendue is a property of light in an optical system that characterizes how "spread out" the light is in area and angle. Etendue can be defined as the product of the light source area or length and the divergence solid angle. The divergence solid angle represents the degree to which light rays spread out from the source. Etendue is relevant in the configuration and operation of display systems, where the quality of the displayed image is influenced by the extent and distribution of light across the display panel.

[0004] In display systems, a pixel is typically composed of subpixels that emit red, green, and blue light. The combination of these colors in varying intensities can produce a range of colors. The arrangement and distribution of the subpixels can affect the visual quality of the display. For instance, gaps between subpixels can lead to visual artifacts, such as the screen door effect, where a visible grid-like pattern of fine lines or gaps between pixels on the screen can be observed.SUMMARY

[0005] Technical advantages are generally achieved, by embodiments of this disclosure which describe display panel with optical layer for etendueconsolidation and screen door effect mitigation and methods for adapting the same.

[0006] In accordance with an embodiment, a device may include an optical layer configured to be disposed over a subpixel of a plurality of subpixels, each subpixel of the plurality of subpixels emitting a beam and corresponding to a color. The device may also include the optical layer that can be configured to combine the beams of each subpixel of the plurality of subpixels and / or to mix the colors of the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch. The device may furthermore include implementations where an overall divergence solid angle of the combined beams can overlap at least 8o percent of a divergence solid angle of each subpixel of the plurality of subpixels.

[0007] Implementations may include one or more of the following features. The device can include implementations where the combined beams having the overall divergence solid angle may include at least 50 percent of light energy emitted by each subpixel of the plurality of subpixels. The device can include implementations where the optical layer is configured to reduce a divergence solid angle of the subpixel to a range between 1 / 3 and 1 / 1000 with respect to a subpixel not having the optical layer disposed over the subpixel. The device can include implementations where the optical layer is configured to reduce the divergence solid angle of the subpixel to a range between 1 / 6 and 1 / 100 with respect to the subpixel not having the optical layer disposed over the subpixel.

[0008] The device can include implementations where a variation in height of a surface of the optical layer is equal or less than 1.5 micron. The device may include the optical layer that can be configured to steer a plurality of beams of a first subpixel to a first angle. The device may include the optical layer that can steer a first color of the first subpixel to combine beams of the plurality of beams.

[0009] The device can include implementations where the optical layer may include a first sublayer and a second sublayer. In some implementations, the first sublayer can be configured to steer a plurality of beams of a first beam of a first subpixel to a first angle and the second sublayer is configured to steer a first color of the first subpixel to combine beams of the plurality of beams. The device can include implementations where a cross-section of a beam profile in a far field is atleast partially elliptical having a ratio of a longer diameter of the beam profile to a lower diameter of the beam profile being in a range between one and 1.5.

[0010] The device can include implementations where projections above the optical layer from active subpixels having a first color at least partially overlap. The device can include implementations where the optical layer is passive. The device can include implementations where the optical layer may include an area of an RGB pixel unit. The device can include implementations where the plurality of subpixels are arranged in a hexagonal pattern. The device can include implementations where the plurality of subpixels are arranged in a strip pattern.

[0011] The device can include implementations where the divergence solid angle of each subpixel of the plurality of subpixels is equal to or less than 0.024 steradian measured at a distance of 20 mm from a top surface of the subpixels. The device can include implementations where an area of an RGB pixel unit is covered by a cross-section profile of the beam being viewed by a microscope having a resolve power equal or finer than 0.5 microns. The device can include implementations where a product of an area of pixels having a display panel having a surface area of 590 mm2and an overall divergence solid angle is less than 14 mm2x steradian.

[0012] In one general aspect, a system may include a display device having an optical layer configured to be disposed over a subpixel of a plurality of subpixels, each subpixel of the plurality of subpixels emitting a beam and corresponding to a color. The system can include implementations where the optical layer is configured to combine the beams of each subpixel of the plurality of subpixels and / or to mix the colors of the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch. The system can include implementations where a divergence solid angle of the combined beams overlaps at least 80 percent of a divergence solid angle of each subpixel of the plurality of subpixels. The system can include implementations where the optical layer is configured to reduce a divergence solid angle from the subpixel to a range between 1 / 3 and 1 / 1000 with respect to a subpixel not having the optical layer over the subpixel. The system can include implementations where the optical layer is configured to reduce the divergence solid angle of the subpixel to a rangebetween 1 / 6 and 1 / 100 with respect to the subpixel not having the optical layer disposed over the subpixel.

[0013] In one general aspect, a method may include disposing an optical layer over a subpixel of a plurality of subpixels, each subpixel of the plurality of subpixels emitting a beam and corresponding to a color. The method can include combining, by the optical layer, the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch. The method may also include implementations where a divergence solid angle of the combined beams overlaps at least 80 percent of a divergence solid angle of each subpixel of the plurality of subpixels.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1 illustrates etendue, according to some implementations.

[0016] Figure 2 illustrates a screen door effect, according to some implementations.

[0017] Figure 3A illustrates an optical system showing an initial state of etendue, according to some implementations.

[0018] Figure 3B depicts the optical system after an initial consolidation of etendue, according to some implementations.

[0019] Figure 3C shows the optical system after further consolidation of etendue, according to some implementations.

[0020] Figure 4 presents an optical system having a hexagonal arrangement of subpixels, according to some implementations.

[0021] Figure 5A illustrates an optical system having a compound parabolic concentrator, according to some implementations.

[0022] Figures 5B-5C illustrate an optical system having a micro-lens, according to some implementations.

[0023] Figures 6A-6B depict an optical system having a display panel with a flat lens, according to some implementations.

[0024] Figures 7 present a schematic representation of an optical system having a strip arrangement of subpixels, according to some implementations.

[0025] Figures 8A-8B present a schematic representation of an optical system for a display panel with sub-pixel pitch expansion and / or divergence solid angle reduction, according to some implementations.

[0026] Figure 9A presents an optical system, according to some implementations.

[0027] Figure 9B illustrates an optical layer having two sublayers, according to some implementations.

[0028] Figures 10A-10C illustrate a color router, according to some implementations.

[0029] Figure 11A presents a top down view of a display panel with an array of subpixels, according to some implementations.

[0030] Figures 11B-11C show cross-sectional views of an optical system, according to some implementations.

[0031] Figures 12A-12C present cross-sectional views of near-held radiation patterns for blue, green, and red light beams, according to some implementations.

[0032] Figures 13A-13C present cross-sectional views of near-field radiation patterns for blue, green, and red light beams passing through an optical layer, according to some implementations.

[0033] Figures 14A-14C depict polar plots of far-held radiation patterns for blue, green, and red light beams, according to some implementations.

[0034] Figures 15A-15C depict polar plots of far-held radiation patterns for blue, green, and red light beams passing through an optical layer, according to some implementations.

[0035] Figure 16 illustrates a diagram of an embodiment processing system, according to some implementations.

[0036] Figure 17 presents a flowchart outlining a method for mitigating the screen door effect in a display panel, according to some implementations.

[0037] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0038] The making and using of embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and that the specific embodiments discussed herein are merely illustrative and do not serve to limit the scope of the claims. Further, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0039] For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features maybe formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and / or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or configurations discussed.

[0040] Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0041] The present disclosure relates to an optical system for display panels, specifically focusing on the consolidation of etendue and mitigation of the screen door effect. The screen door effect is a visual artifact that occurs in digital displays, where the fine lines separating pixels become visible, disrupting the viewing experience. This effect can be, for example, in high-resolution display systems, where the small size of subpixels and the gaps between them can create a pixelated effect, similar to a view of an image observed through a screen door.

[0042] Non-imaging optics, such as light concentrators, can be used in optical systems to manipulate the divergence solid angle or spot size of light, whileconserving etendue. The solid angle fl is a measure of the amount of the field of view from a point that a given object covers. The solid angle can be measured in steradians. In some implementations, the steradian can be expressed as m2 / m2. The solid angle f can be expressed using the following equation:

[0043] fl = A / r2

[0044] where fl is the solid angle, measured in steradians (sr); A is the surface area of the portion of the sphere subtended by the solid angle; r is the radius of the sphere.

[0045] One steradian can correspond to the solid angle subtended by a surface area equal to the square of the radius of a sphere at the center of the sphere. In other words, a solid angle of one steradian is subtended by a portion of a spherical surface with area equal to the square of the sphere radius.

[0046] The divergence solid angle (the beam divergence or beam spread), can be a measure of how much a light beam spreads out as the light beam propagates through space. The divergence solid angle is defined as the solid angle through which the majority of the beam power is emitted.

[0047] Etendue is a property of light in an optical system that describes the extent of a light field in terms of the product of a size of the light source and a divergence solid angle of the light. Etendue influences the efficiency of light coupling and the overall visual quality of the display. The principle of conserving etendue, also known as the Lagrange invariant, can apply to lossless optical systems.

[0048] In the field of display technology, there is a trend towards larger display panels and higher resolutions. This trend is driven by the desire for more immersive viewing experiences and sharper image quality. These improvements present challenges in terms of managing etendue of the display panel. As the pixel unit size decreases and the panel size increases, etendue becomes larger, making it more difficult to couple or collect light efficiently. This can cause at least partially a loss of image clarity and a reduction in the overall quality of the display.

[0049] The present disclosure addresses this technical issue by introducing an optical layer, such as a non-imaging cover layer or phase mask, which is configured to be disposed over the subpixels of a display panel. In some embodiments, the optical layer may be formed of flat lens (as further describedbelow). The subpixel emits a beam of light corresponding to a specific color, e.g., red, green, or blue (RGB). The optical layer is configured to expand the light beam from the subpixel to cover an area corresponding to a full pixel pitch. This process effectively combines the light beams from the subpixels having the same color, filling the gaps between them and reducing the divergence solid angle of the combined beam.

[0050] In some implementations, the optical layer can consolidate etendue of the subpixels. As an example, by expanding the light from the subpixel to cover the full pixel pitch, the optical layer effectively reduces the divergence solid angle of the light, thereby consolidating etendue of the subpixel and reducing the overall divergence solid angle of the display panel.

[0051] The present disclosure provides several benefits. By reducing the gaps between the subpixels, the screen door effect can be effectively mitigated, improving the visual quality of the display. By consolidating etendue of the subpixel, the present disclosure can improve the efficiency of light coupling in the display panel, which can lead to brighter and more vibrant images.

[0052] Figure i illustrates etendue in an optical or display system that can include a display panel. Etendue is a property of light that quantifies the spatial and angular extent of a light beam. Etendue can be determined by the product of surface area of the light source and the solid angle into which the light is emitted.

[0053] A light source with a surface size of Ax can emit light rays that diverge at an angle A0x. The surface size Ax represents the physical dimensions of the light-emitting area, and the divergence angle A0x indicates the angular spread of the emitted light rays.

[0054] Etendue of the light source can be expressed as the product of Ax and A0x. This relationship illustrates the interdependence of the spatial and angular extents of the light field. The larger the surface size or the divergence solid angle, the higher etendue of the light source. A light source with a larger surface area will have a higher etendue, as will a source with a wider divergence solid angle.

[0055] The relationship between the expanded illumination area and the reduced divergence solid angles can be approximated using the principle of etendue conservation. Etendue, which can be defined as the product of the area and the solid angle of the light beam, remains constant in a lossless optical system. The lossless optical system produces an image with the same etendue asthe source. Etendue does not decrease in the optical system in which an optical power is conserved. Etendue is related to the Lagrange invariant and the optical invariant, which share the property of being constant in an ideal optical system.

[0056] Assuming the original sub-pixel area is A and the expanded circular area is A', etendue conservation equation can be written as equation (i):

[0057] A x £1 < A' x £1' (1),

[0058] where fl and fl' are the solid angles of the light beam before and after passing through the optical layer, respectively.

[0059] The radiance can refer to a radiant flux per unit solid angle per unit area. The radiance can quantify the amount of radiant energy passing through an area in a particular direction. The radiance can represent the brightness or intensity of light emitted or transmitted by an optical system. The radiant flux is the total amount of radiant energy passing through a given surface per unit time.

[0060] The relationship between the radiance and etendue can be defined by the derivative of the radiant flux with respect to etendue. As described herein etendue is a measure of the spatial extent and the angular range of light rays that can pass through an optical system. The derivative of radiant flux with respect to etendue provides a measure of how efficiently the optical system can capture and transmit light.

[0061] Figure 2 illustrates the screen door effect (SDE). The SDE can be a visual artifact that appears in display devices, e.g., near-eye displays, such as virtual reality displays, characterized by a visible grid-like pattern of fine lines or gaps between pixels or subpixels on the screen, resembling a screen door. The SDE can be caused at least partially by noticeable gaps between pixels or subpixels, which can be large enough to be resolved by the typical viewing optics, thereby creating a relatively disruptive visual effect. These visible gaps can compromise the immersive experience for users. The SDE can degrade the overall image quality and immersion, e.g., in high-resolution displays where individual pixels are more discernible.

[0062] Figure 3A illustrates an optical system showing an initial state of etendue, according to some implementations. A display panel can emit light to form an image. As an example, the display panel can be configured to display images to the target or viewer. The display system can include a device 300. Specifically, the device 300 can be a light field device. In some implementations,the device 300 includes light-emitting units or pixels. Each pixel can include a plurality of subpixels 314 emitting light of specific colors. In the display panels, the subpixel 314 can be a light source. The pixel can typically include three subpixels (e.g., 314a, 314b, and 314c) that emit light of a specific color. The subpixels 314 are typically arranged in a periodic array, with each subpixel 314 emitting light of a specific color, such as red (R), green (G), and blue (B) lights. The combination of these colors in varying intensities can produce a range of other colors.

[0063] Each light-emitting unit or pixel emits one or more light fields. In this context, a light field is described by a vector function that describes the amount of light flowing in a plurality of directions through a plurality of points in space. Specifically, alight field includes a plurality of light rays or light beams (e.g., 316 and 318) defined by a plenoptic function. Each light ray 316 or 318 has a radiance, which is a measurement of the amount of light traveling along the light ray 316 or 318. Put another way, each light-emitting unit or pixel emits a plurality of light rays such as 316 and 318.

[0064] In the illustrated example, only some of the light rays 316 and 318 radiating toward the target or viewer are illustrated. Each of the light rays 316 and 318 travels in a direction that forms an acute angle with a direction that is orthogonal to a major surface of the device 300. As such, an appearance of the image may be created by the light rays (e.g., 316 and 318) that are emitted by the light-emitting units or pixels.

[0065] The light source or the subpixel 314 with a surface size of Ax (e.g., Ab for the blue subpixel 314b) emits light with a divergence angle of A0x (e.g., A0b for the blue subpixel 314b). A divergence angle can be an angle at which light rays spread out from a source. Etendue of the light source is the product of the surface size Ax and the divergence angle A0x; etendue represents the extent of the light field.

[0066] Due to manufacturing constraints and the electrical interconnects, there can be gaps between adjacent subpixels 314. These gaps do not emit light and can appear as dark spaces in the display. When the subpixels 314 are sufficiently small and closely spaced, a human eye may perceive these gaps as a visible grid-like pattern known as the SDE. The SDE is more visible when etendue of the subpixels 314 is high. A larger subpixel size results in a greater surface area,increasing etendue. A wider emission angle from the subpixels 314 contributes to a higher etendue. As etendue of the subpixels 314 increases, the light emitted from the subpixel 314 becomes more spread out and diffused, making the gaps between subpixels 314 more apparent.

[0067] To mitigate the screen door effect, reducing divergence solid angle of the display system can be beneficial. Such method of reducing the divergence solid angle can reduce the size of the subpixels 314 and the gaps between them. However, this method may cause manufacturing challenges and may affect the overall brightness and efficiency of the display. An alternative solution is to employ optical techniques that can expand the light emitted from the subpixel 314 to cover a larger area, effectively reducing the perceived gaps and reducing the screen door effect.

[0068] The present disclosure provides an optical layer 310 (see Figure 3B). The optical layer 310 can be disposed over the subpixels 314 in a display panel. The optical layer 310 can be configured to expand the light emitted from the subpixel 314 to cover an area corresponding to the full pixel pitch, thereby reducing the divergence solid angle and creating an overlapping illumination pattern that fills the gaps between the subpixels 314. By manipulating the light field and redistributing etendue, the optical layer 310 reduces the visual impact of the screen door effect while substantially maintaining the original subpixel dimensions and resolution.

[0069] Figure 3B depicts the first stage of divergence angle reduction in the display system. When the subpixels 314 are spaced apart, each subpixel 314 (e.g., the subpixel 314g corresponding to the green color) can emit light with a divergence angle A0g (see also Figure 3A). This divergence angle represents the angular spread of the light rays emanating from the subpixel 314. A larger divergence angle indicates a wider cone of light emission, which can contribute to a higher etendue and increase the screen door effect.

[0070] The optical layer can be disposed over the top surface of the subpixels (e.g., over the subpixels 314a, 314b, and 314c). When the optical layer 310 is used, it interacts with the light emitted from the subpixel 314 and can alter spatial distribution of the light. The optical layer 310 is configured to expand the illumination area of the subpixel 314, causing the light to spread out over a larger surface area. This expansion is achieved through a combination of refraction,diffraction, and waveguiding effects, at least partially depending on the configuration of the optical layer 310.

[0071] As a result of the expanded illumination area (denoted as Di in Figure 3B) when, e.g., the subpixels 314b, 314g, 3i4r are not spaced apart from each other, the divergence angle of the light emitted from the subpixel 314 is reduced from A0g to A0g2. This reduction in divergence angle provides the light rays that are more concentrated and collimated, propagating within a narrower cone (illustrated by the narrower angle between the rays 316 and 318). The optical layer 310 redirects and focuses the light, providing the light covering a larger portion of the pixel pitch without substantially increasing the angular spread.

[0072] The expansion of the illumination area and the reduction of the divergence angle occur while maintaining substantially the same overall display panel size Di. The optical layer 310 does not physically enlarge the subpixels 314 or the display panel itself. In some implementations, the optical layer 310 improves the distribution of light within the existing pixel pitch, using the available display area.

[0073] By expanding the illumination area and reducing the divergence solid angle, a lower overall etendue of the display system can be achieved. Etendue, as discussed in Figure 1, is the product of the light source surface area (e.g., the surface area of the subpixel 314) and its emission angle. In Figure 3B, the effective surface area of the subpixel 314 is increased, while the emission angle is decreased. This combination leads to an overall reduction of the divergence solid angle, indicating that the light is more efficiently concentrated and directed toward the viewer.

[0074] Reducing divergence solid angle has several benefits for the display quality. The reduction of the divergence solid angle can provide mitigation of the screen door effect by filling in the gaps between subpixels 314. As the illumination area of the subpixel 314 expands, the dark spaces between the subpixels 314 become less noticeable, creating a more seamless and continuous image. In some implementations, the reduced divergence solid angle improves the overall brightness and contrast of the display. With the light rays being more focused and collimated, a higher percentage of the emitted light reaches the viewer eyes, resulting in a brighter and more vivid image.

[0075] Figure 3C demonstrates further divergence angle reduction achieved by the optical layer 310. The subpixel illumination areas are expanded to overlap each other, creating a relatively seamless emission surface. The divergence angle is further reduced to A0g3, resulting in a lower etendue for the display panel.

[0076] Figure 3C illustrates overlapping of the subpixel illumination areas. The overlapping creates a relatively seamless emission surface, reducing visible gaps or dark spaces between the subpixels 314. As a result of the overlapping illumination areas, the divergence angle of the emitted light is further reduced from A0g2 to A0g3. This additional reduction in the divergence angle provides the light rays that are more collimated and focused, propagating within a narrower cone compared to the previous stage in Figure 3B.

[0077] The combination of overlapping illumination areas and the reduced divergence solid angle can result in a lower etendue for the display panel. Etendue, as previously discussed, is the product of the light source surface area and its emission solid angle. By increasing the overlap of illumination areas and reducing the divergence solid angle, an improved spatial and angular light distribution can be achieved.

[0078] In some implementations, the optical layer or phase mask 310 can be used to expand the light from each sub-pixel 314 (e.g., red, green, or blue subpixel 3i4r, 314g, 314b, respectively), to the full size of each pixel pitch. Such expansion can increase the area covered by the light from each sub-pixel 314 by a factor of three to 40 times, at least partially depending on the configuration of the device 3OO.

[0079] As an example, by conserving etendue, the optical layer 310 provides the exit cone angle of the light that can be reduced to a range of i / 3rd to i / 4Oth from the area point of view. With etendue at a relatively low value, the light emitted from the subpixels 314 is efficiently concentrated and directed.

[0080] In some implementations, the optical layer 310 may be configured to eliminate or substantially reduce gaps between subpixels 314 in full-color display panels. In some implementations, an active pixel area of each subpixel 314 can be less than i / 3rd of the overall pixel area. By expanding the active pixel area of each RGB subpixel 314, which may constitute approximately i / 3rd to 1 / ioooth of the overall pixel area, the optical layer 310 can substantially remove or reduce the gaps between the subpixels 314. In some implementations, the active pixel area ofeach RGB subpixel 314 can be approximately in a range between 1 / 6 and 1 / 100 of the overall pixel area.

[0081] Although etendue may not be decreased, etendue can be consolidated from a display panel perspective. The optical layer 310 achieves etendue consolidation by expanding the light from each sub-pixel 314 (e.g., red, green, and blue subpixel 3i4r, 314g, 314b, respectively) to the full size of the pixel pitch, which may result in an area expansion in the range of 3 to 1000 times. Such expansion allows for the mixing of light from the RGB subpixels 314, consolidating etendue from each subpixel 314. In some implementations, the exit cone angle 0 of the light is reduced to a range of i / 3rd to 1 / 1000th from the area point of view, which consolidates the overall etendue of the display device 300. In some implementations, the optical layer 310 can reduce the divergence angle 0 of the subpixel 314 to a range between 1 / 6 and 1 / 100 with respect to the subpixel 314 not having the optical layer 310 disposed over the subpixel 314.

[0082] The reduction of gaps between subpixels 314 and the collimated light emission contribute to improved contrast ratios. The relatively seamless emission surface prevents light leakage and reduces the impact of ambient light, resulting in deeper black shades and more vivid colors.

[0083] The optical layer 310 can control the angular distribution of light providing the display that maintains its brightness and color across a wide range of viewing angles. Such feature can be beneficial for applications where multiple viewers may be present or where off-axis viewing is common.

[0084] The overlapping illumination areas and the reduced divergence solid angle provide a higher percentage of the emitted light to reach the viewer eyes. Such increased light efficiency provides a brighter and more vibrant display, which can be achieved, for example, at lower power consumption levels.

[0085] By reducing divergence solid angle and improving the light distribution, improved visual performance with lower power consumption can be achieved. The improved energy efficiency is beneficial for, e.g., portable devices, such as smartphones and virtual reality headsets, where battery life is important.

[0086] Figure 3C illustrates a relatively seamless emission surface, achieved through overlapping illumination areas, and the collimated light emission, resulting from the reduced divergence solid angle. By reducing the limitations caused by the screen door effect and inefficient light distribution, the presentdisclosure provides the displays with higher pixel densities, improved brightness, and improved visual immersion.

[0087] Figure 3C illustrates divergence angle reduction in the display system, achieved through the improved configuration. By overlapping the subpixel illumination areas or reducing the divergence solid angle to a relatively low value, the optical layer 310 provides a relatively seamless emission surface and increases the optical efficiency of the display system. Such divergence reduction reduces the screen door effect and improves the brightness, contrast, viewing angles, and energy efficiency of the display. The improvements demonstrated in Figure 3C can provide improved visual quality and immersive experiences.

[0088] In typical display systems, a diffraction-limited divergence angle can occur. For circular spots, the half divergence angle, denoted as 9o, can be determined by equation (2):

[0089] 6o = 1.22X / D’ (2),

[0090] where X represents the wavelength of the light and D' is the diameter of the aperture through which the light is passing. Such relationship can be caused by diffraction of light, which occurs when light waves encounter an obstacle or opening, such as an aperture, that disrupts the propagation of the light waves. Equation (2) can express the diffraction limit for a circular aperture, which can be referred to as the Airy disk formula.

[0091] Typical optical diffusers can expand the cone angles and increase etendue. The SDE can occur when the resolution of the display is lower than the sharpness of the displayed image. To reduce the SDE, the display resolution can be increased or algorithms can be used to relatively slightly blur the image, making the grid less noticeable. Optical devices such as diffusers can be used to reduce the grid pattern by softening the sharp edges of the pixels. The typical diffuser can expand the divergence cone angle within the optical stack, thereby increasing etendue. Adding the diffuser can increase the cone angle, denoted as 0cone by increasing the original cone angle 0e. Such relationship can be expressed in the following equation: 0COne = 0e+ ©diffuse > 0e. Such expansion of the divergence cone angle can reduce the quality of the optical stack.

[0092] To reduce the SDE, piezo actuators can be used to shake the display. Such method implements shifting the pixels. By shaking the display, the gaps between pixels can be reduced, making the pixels appear larger and closertogether, thus minimizing the SDE. However, to implement the method of shaking the display, it may be required for the display to operate at a relatively high frame rate of, e.g., 240 frames per second, for which an increased display bandwidth is needed.

[0093] Figure 4 depicts a hexagonal arrangement of pixels, each pixel including of red (R), green (G), and blue (B) subpixels. The hexagonal pattern can be a geometric arrangement where the subpixel is surrounded by six other subpixels in a hexagonal shape. In some implementations, the optical device can be configured to mix and combine RGB illumination.

[0094] A typical compound parabolic concentrator (CPC) can be an optical device that is configured to project the light from a small surface to a larger aperture, while reducing the divergence solid angle of the light. The pixel unit size may be attempted to be reduced in order to accommodate more pixel units in the display systems. For example, larger panel sizes may be created in order to achieve a wider field of view (FOV). The wider FOV, reaching up to 120 degrees (or 3.142 steradian), can provide a more immersive viewing experience, particularly in applications such as virtual reality displays.

[0095] Higher resolutions may be desired to achieve a so-called "retina display" or a resolution higher than 30 cycles per degree. Such level of resolution of the retina display is high enough for a human eye to discern individual pixels, resulting in relatively clear and detailed images. As the pixel size decreases, the divergence solid angle of the light, or the angle at which light rays spread out from the pixel, increases. When combined with the larger panel size, it results in relatively larger etendue. Larger etendue can make it more difficult to efficiently couple or collect light, potentially causing a loss of light intensity. By projecting light from a smaller surface to a larger aperture while reducing the divergence solid angle, the CPC attempts to manage etendue of the optical system, thereby improving the efficiency of light coupling and collection.

[0096] Figure 5A illustrates an optical system implementing CPCs or microconcentrators. The reduction in divergence solid angle can improve optical efficiency and mitigate the screen door effect. For example, a typical OLED 4K display panel can have a high resolution with 8 million pixels, each pixel having a pitch of about 2.3 micrometers in diameter for the individual sub-pixels (e.g., red, green, and blue subpixels). The green light emitted by the display can have awavelength of 550 nanometers, and the half angle of light emitted can be calculated to be approximately 16.6 degrees (0.29 radian or 0.071 steradian). To capture and utilize this light, relatively large and heavy optical components may be needed due to the numerical aperture of 0.3, which determines the lightgathering capability of the display system.

[0097] Typical devices using compound parabolic concentrators can use lightemitting pixels or so-called nano-pixels having a size of I3onm. The light emitted from the nano-pixels spreads out using compound parabolic concentrators that expand the light to a size of 263nm. Such expansion can control the direction and angle at which the light spreads out. At the expanded size of 263nm, the light emitted from the nano-pixels can still have a relatively high divergence solid angle. As an example, such divergence angle can be as high as 2.55 radian (or 146 degrees or 4.457 steradian), as calculated using equation (2): 0O= 1.22X / D'.

[0098] Using the micro-concentrator method, the divergence angle can be reduced to 0e « 0p / 4, where 0p is the original pixel angle. The micro- x / *3 concentrator method can result in a linear divergence angle reduction of As described herein, the present disclosure achieves a higher reduction in divergence angle in comparison to the micro-concentrators, leading to a greater improvement in optical performance.

[0099] Figures 5B-5C illustrate an optical system having a micro-lens. In the typical micro-lens method, each subpixel can be covered with a microlens to expand the emitted light. As illustrated in Figure 5B, the expanded illumination area can be hexagonal. The diameter of each microlens can be related to the pixel pitch D and can be expressed as: Microlens diameter = (2 / 3)D, where D is the pixel pitch.

[0100] Such diameter can provide the microlens that cover the sub-pixel and allow for the collimation of light. The separation between two neighboring subpixels in a hexagonal arrangement can be expressed through the following equation: Separation between two neighboring subpixels = (y) D.

[0101] As illustrated in Figure 5C, the divergence angle 0e after light passes through the microlens can be derived from the geometry of the microlens and the initial divergence angle 0p. The microlens can collimate the light emitted from the sub-pixel, reducing the divergence angle. The relationship between the initialdivergence angle 0p and the reduced divergence angle 0e can be expressed as: 0e ® V3 0p / 4. Since the divergence angle can be reduced to approximately to V3 0p / 4, it can lead to a linear reduction by V3 / 4- The microlens can collimate the light to a smaller divergence angle, and the factor of A / 3 / 4 represents the reduction of the divergence angle using the microlens.

[0102] For example, the hexagonal arrangement of pixels with a pitch of D being 7 pm results in a separation between neighboring subpixels of V3 / 3 D. The hexagonal-shaped microlens with a circular diameter of (2 / 3)D can be used, assuming the subpixel diameter is half the neighboring distance at V3 / 3 D. A collimation of the light cone to 0e ~ V3 0p / 4 can be achieved.

[0103] By placing a hexagonal shaped microlens with a circular diameter of ( 3 / 3) D over each sub pixel, the light cone can be collimated, reducing the divergence angle by more than two times achieving a similar reduction of the divergence angle. Despite such reduction, the gaps between subpixels may still be visible due to the limitations of the microlens imaging system. The visibility of these gaps can contribute to the screen door effect.

[0104] Typical devices can have the microlenses, which can be positioned on top of each pixel (where each pixel can include a plurality of subpixels) to manipulate the light paths in an attempt to reduce the screen door effect by filling in the gaps between subpixels, thus attempting to create a more continuous and seamless visual experience in an imaging plane.

[0105] The imaging plane in a display system is the surface where the light from the display pixels is intended to form a visible image for the viewer. For LCDs, OLEDs, or micro-LED displays, the imaging plane can be the actual screen surface that the user views.

[0106] The light from each subpixel, which enters the microlenses at different angles, can be focused at distinct positions on the imaging plane because the f- theta rule provides the position of the focused spot on the imaging plane being a function of the angle of incidence (0) and the focal length (f) of the lens, with the relationship expressed as P = f x 0. Since the RGB subpixels are spatially separated, the light from each subpixel can have a different angle of incidence when it enters the microlenses, leading to different focal points on the imaging plane.

[0107] According to the f-theta rule, as the angle of incidence (9) increases, the position of the focused spot or the distance (P) from the optical axis to the focused spot (where the light is focused on the plane) increases proportionally. Such relationship is also true for small angles. In the devices using microlenses on a display, the f-theta rule indicates that light rays from RGB subpixels entering at different angles can focus at different positions on the imaging plane. It can lead to a separation of the focal points for each color, which is undesirable for color mixing and it can result in a display with visible subpixel structures and color inaccuracies.

[0108] Instead of merging into a single, well-mixed spot of color on the imaging plane, the light from each RGB subpixel may remain separate, leading to a failure to properly combine the colors. This can cause color fringing, inaccuracies, and the screen door effect, where the individual subpixels remain visible, detracting from the overall image quality. Therefore, the microlens approach, without additional optical configurations, may not be sufficient to achieve the desired outcome of effective color mixing on the imaging plane of the digital display.

[0109] Figures 6A and 6B illustrate the aspects of the present disclosure providing overlapping illumination. The approaches used by the display devices 6oo having an optical layer 610 provide high-quality, immersive display systems with reduced screen door effect and improved optical efficiency.

[0110] In some implementations, Figures 6A and 6B illustrate the configuration of the optical layer 6io for a hexagonal subpixel arrangement. In some implementations, the device 6oo can include the optical layer 6io disposed over the subpixels 614. The optical layer 610 is configured to expand the light from the subpixel 614 to cover an area corresponding to a full pixel pitch, thereby reducing the divergence solid angle of the light and creating an overlapping illumination pattern that mixes the colors relatively seamlessly.

[0111] In some implementations, the present disclosure described in Figures 6A-6B uses the optical layer 610 to mix and overlap the illumination from adjacent sub-pixels 614 of the same color, reducing the visible boundaries between the adjacent sub-pixels 614 of the same color.

[0112] As illustrated in Figure 9A, the optical layer 610 expands the illumination area of the subpixel 614 to a circular shape with a diameter of (2 V3 / 3)D, where D is the pixel pitch. As an example, the optical layer 610 can beconfigured to project the sub-pixel to a circle having the diameter of (2 V3 / 3)D on a top surface 620 of the optical layer 610. This expansion allows for mixing of colors and reduction of visible subpixel boundaries. The overlapping illumination areas from, e.g., green subpixels 6i4gi, 6i4g2, 6i4g3covers the full pixel pitch, creating a continuous emission surface that substantially reduces or eliminates the screen door effect. Areas 616 and 618 represent overlapping illumination areas from three different colors of, e.g., subpixels 6i4n, 6i4bi, and 6i4g2for the area 616 and subpixels 6i4r2, 6i4bi, and 6i4g2for the area 618.

[0113] In some implementations, an OLED panel can have a diagonal distance of 1.35 inches. The overall divergence angle after collimating by the optical layer 610 can be five degree half linear angle or 0.024 steradian solid angle (see Figures 15A-15C). The product of the area of pixels having such display panel and an overall divergence solid angle can be less than 14 mm2x sr.

[0114] As an example, the 1.35" diagonal panel can have a surface area of 590 mm2. A half angle of five degrees (equivalent to a full angle of ten degrees in linear measurement) corresponds to a solid angle of 0.024 steradian. By considering the product of the surface area and the solid angle measured in steradians, multiplication of these values yields a result of 14 mm2x sr (square millimeters times steradians).

[0115] Figure 6A demonstrates the effect of the overlapping illumination technique on the subpixel level. The device 600 using the optical layer 610 expands the illumination area of the subpixel 614, e.g., the subpixel 6i4g2, to overlap with neighboring subpixels 614 of the same color, e.g., the subpixel 614g! and 6i4g3. By expanding the illumination area of the subpixel 614 to a circular shape with a diameter of (2 V3 / 3)D, the light from adjacent subpixels 614 of the same color overlaps, creating a continuous illumination area. Such overlapping reduces the visible gaps and reduces the divergence solid angle of the emitted light.

[0116] As shown in Figure 6B, the present disclosure utilizes a flat lens to reduce the divergence solid angle of the emitted light. The flat lens or metalens can be a type of the optical layer 610 that can manipulate light on a subwavelength scale. As an example, the flat lens can be an optical element that manipulates the phase and amplitude of the light waves, providing control over the light distribution.

[0117] In some implementations, the subpixel 614 can have the initial divergence angle 0p / n of the light emitted from the subpixel 614, where n is refractive index of the media. Refractive index can be defined as the ratio of the speed of light in a vacuum to the speed of light in the material. A higher refractive index indicates that light travels more slowly in the material, causing light to bend or refract when light enters or exits the material. This bending of light allows lenses to, for example, focus or magnify images.

[0118] The refractive index can determine how light interacts with a material. As an example, different materials can have different refractive indices, which can vary depending at least partially on factors such as wavelength and temperature. By controlling the refractive index of materials, the optical device 600 can be configured with specific properties.

[0119] Without the overlapping illumination technique, the light from the subpixel 614 can be confined to its own discrete area, resulting in visible gaps between subpixels 614 and potential color non-uniformity. By configuring the flat lens structure, the divergence angle can be reduced to 9e ® 0p / n, where n is refractive index of the media resulting in a substantial divergence solid angle reduction and improved light collimation.

[0120] Figure 6A illustrates the subpixel illuminating a circular area with a diameter of (2 V3 / 3)D, where D represents a distance between two closest subpixels of the same color, e.g., 6i4g4and 6i4g5. In some implementations, distance D can be, for example, a value of the pixel pitch or the distance between the centers of adjacent pixels. A value of (V3 / 3)D can represent a distance between two closest subpixels of different colors, e.g., 6i4b2and 6i4g5. In some implementations, the optical layer can be configured to manipulate the light emitted from the subpixels 614. As an example, the optical layer 610 can be configured to expand the light from the subpixel 614 to cover an area corresponding to a full pixel pitch. The blending of light from neighboring subpixels 614 of the same color (e.g., 6i4gi, 6i4g2, and6i4g3) provides a smooth transition between colors and reduces potential color fringing or artifacts that may arise from distinct subpixel boundaries. By expanding the illumination area to cover the full pixel pitch, the gaps between subpixels 614 can be effectively reduced, creating a relatively continuous and uniform color appearance across the entire or substantially entire pixel area.

[0121] The derivation of the illumination diameter (2 V3 / 3)D is based on the geometry of the hexagonal pixel arrangement. As an example, in a hexagonal grid, the distance between the centers of adjacent pixels can be (V3 / 2)D. To provide an appropriate overlapping and gap reduction, the diameter of the circular illumination area is about twice this distance, resulting in the following equation 2 x (V3 / 3)D = (2 A / 3 / 3)D.

[0122] The described overlapping illumination technique provides several advantages over approaches implemented by the display devices that do not use the optical layer 610, such as the devices having the micro-concentrator configuration (e.g., as shown in Figure 5A). In typical devices not using the optical layer 610, a micro-concentrator can be disposed over a top surface of each subpixel to expand the light to a limited extent (typically to a hexagonal shape with a circle diameter of (2 / 3)D, where D is the pixel pitch). The microconcentrator method can reduce the divergence angle linearly to V3 / 4. Gaps between subpixels may still be visible. While the micro-concentrator approach expands the illumination area to a hexagonal shape with a circle diameter of (2 / 3)D, it can still leave visible boundaries between the subpixels 614, and the screen door effect may not be effectively mitigated.

[0123] Figure 6B illustrates the optical layer 610 which can include the flat lens. The flat lens optical layer 610 is placed over the subpixels 614 and expands the illumination areas of the subpixels 614 to cover the full pixel pitch. In some implementations, the optical layer 610 reduces the exit divergence angle 6e of the light beams, preventing or substantially reducing undesired crosstalk between adjacent pixels.

[0124] In some implementations, when the optical layer 610 expands the illumination area of the subpixel 614 to cover the full pixel pitch, the optical layer 610 can reduce the visibility of the gaps between subpixels 614, creating a more seamless and relatively continuous image. The flat lens structure of the optical layer 610 can include subwavelength-scale elements that manipulate the phase and amplitude of the incident light. These elements are arranged in a pattern to control the propagation and distribution of light emitted from the subpixel 614. By improving the configuration of the subwavelength-scale elements, the opticallayer 610 can shape the light beam of the subpixel 614 and expand the coverage area of the subpixel light beam to cover the full pixel pitch.

[0125] The exit divergence angles can be denoted as 0e. By reducing the divergence angle, the optical layer 610 provides the light beams from adjacent subpixels 614 that do not overlap or interfere with each other, substantially reduce or prevent crosstalk and substantially maintain the integrity of the displayed image.

[0126] The reduction in exit divergence solid angles is achieved by using the flat lens structure. The subwavelength-scale elements of the optical layer 610 are configured to modify the phase front of the emitted light, effectively collimating the light beams and reducing their angular spread.

[0127] To quantify the improvement in display quality achieved by the optical layer 610, the relationship between the expanded illumination area and the reduction in exit divergence solid angles is described herein. The expanded subpixel pitch, denoted as (2 V3 / 3)D, represents the increased area covered by the light after passing through the optical layer 610. The expansion factor of 2 V3 / 3 is derived from the hexagonal arrangement of the subpixels 614, where D represents the original pixel pitch.

[0128] As an example, in a hexagonal pixel arrangement, the distance between the centers of adjacent pixels is equal to the pixel pitch D. To achieve overlapping and gap reduction, the circular illumination area has a diameter that spans the distance between the centers of two adjacent pixels in the hexagonal arrangement. In a hexagonal grid, the distance between the centers of adjacent sub-pixels 614 of different color can be (V3 / 3)D. To provide overlapping and gap reduction, the diameter of the circular illumination area is about twice this distance, e.g., 2 x fy / 3 / 2)D = (2 V3 / 3)D. By expanding the illumination area to (2 V3 / 3)D, the optical layer 610 reduces the exit divergence angles 0e.

[0129] From Equation (1), the solid angle is proportional to the square of the divergence angle, so fl oc 0A2 and fl' oc 0'A2, where 0 represents the original divergence angle and 0' represents the reduced divergence angle after passing through the optical layer 610.

[0130] Substituting these relationships into etendue conservation equation (1) yields:

[0131] A x 0A2 = A' x 0’A2

[0132] In some implementations, the reduced divergence angle 0’ can be approximately 1 / 4 of the original divergence angle 0:

[0133] 0’ ~ (1 / 4) x 0

[0134] The optical layer 610 is advantageous over the display devices not using the optical layer 610, such as the micro-concentrator devices (see Figure 5A), because the optical layer 610 can achieve a more substantial reduction in exit divergence solid angles while maintaining a relatively seamless and continuous illumination area. The micro-concentrator approach expands the illumination area to a hexagonal shape with a circle diameter of (2 / 3)D. The microconcentrator approach exhibits visible boundaries between the subpixels 614 and achieves a lower reduction in exit divergence angles, with 0e » 0p / 4 and a linear divergence angle reduction of V3 / 4-

[0135] In some implementations, the optical layer 610 in the present disclosure expands the illumination area to a circular shape with a diameter of (2 V3 / 3)D, effectively reducing the visible boundaries between subpixels 614. In some implementations, the flat lens structure of the optical layer 610 provides a higher reduction in exit divergence angles, with 0’ = (1 / 4) x 0, leading to a greater improvement in optical performance and image quality.

[0136] The present disclosure provides more effective mitigation of the screen door effect and improves the visual performance of display panels compared to the micro-lens method. For example, the optical layer 610 can achieve full pixel pitch coverage, greater reduction in the divergence solid angle, more effective overlapping of illumination areas, and improved optical efficiency.

[0137] The present disclosure uses the optical layer 610 that expands the light from each subpixel 614 to cover the full pixel pitch, providing substantially no visible gaps between the subpixels 614. The optical layer 610 can provide a resulting divergence solid angle to overlap at least 80 percent of the divergence solid angle of each subpixel 614, resulting in a more uniform and seamless display appearance. In some implementations, the combined beams having the overall divergence solid angle can have at least 50 percent of light energy emitted by each subpixel 614. The optical layer 610 can be passive; for example, the optical layer 610 may not require active components, such as electronic or moving parts, for functioning of the optical layer 610. As an example, the optical layer 610 can usethe inherent physical properties of the materials or the manufacturing configuration to achieve the appropriate manipulation of light in the optical system.

[0138] The flat lens configuration of the optical layer 610 offers advantages over typical devices that do not use the optical layer 610. In some implementations, the optical layer 610 can include one layer having a thickness of 2pm, which is relatively lightweight and can be integrated into existing display manufacturing processes. The optical layer 610 can be relatively lightweight, offering a relatively straightforward and cost-effective solution that can be integrated into display manufacturing processes without the relative complexity of, e.g., aligning individual microlenses with the corresponding subpixels.

[0139] By consolidating etendue and reducing the total or overall divergence solid angle, the present disclosure improves the optical efficiency of the display system, leading to relatively brighter and more vibrant images with improved contrast ratios.

[0140] In some implementations, the modulation transfer function (MTF) can describe the optical system capability to transfer contrast from the object, e.g., from the subpixels 614, to the imaging plane, which can be the combined RGB emission surface 620. A higher MTF indicates better image quality, characterized by sharper edges and reduced blurring.

[0141] The improvement in display quality facilitated by the optical layer 610 can be expressed using the following metric: full-width at half-maximum (FWHM) of the light beam after passing through the optical layer 610. FWHM can be calculated as follows:

[0142] FWHMe = 2 x arctan(0e / 2),

[0143] where FWHMe represents the angular full-width at half-maximum.

[0144] Similarly, the MTF of the optical system can be determined by considering the spatial frequency response of the optical layer 610 and the arrangement of the subpixels 614. The MTF is a function of the spatial frequency f and can be expressed as:

[0145] MTF(f) = |OTF(f)|,

[0146] where OTF(f) is the optical transfer function, which is the Fourier transform of the point spread function (PSF) of the optical system.

[0147] Figure 6B illustrates that by expanding the illumination area of the subpixel 614 to cover the full pixel pitch and reduce the exit divergence angles 0e, the optical layer 610 reduces the screen door effect and improves the optical efficiency of the display system. The derivation of the expanded sub-pixel pitch (2 V3 / 3)D and the reduced divergence angle 0' « (1 / 4) x 0 illustrates the improvements achieved by the optical layer 610 compared to the display devices not using the optical layer 610. The optical layer 610 provides the relatively seamless and continuous appearance of the displayed image, resulting in a high- quality visual experience.

[0148] In some embodiments, subpixels 614 can be laid out in a checkerboard array. In a checkerboard subpixel array, the subpixels 614 can be aligned along diagonal directions, in the top-down view. Other acceptable pixel shapes maybe utilized. For example, the subpixels 614 may have other polygon shapes. In some implementations, the subpixels 614 may have non-polygon shapes.

[0149] Figure 7 present a schematic representation of an optical system, according to some implementations. The display system can be arranged in a strip pattern. The strip pattern can be an arrangement where subpixels are aligned in a linear sequence or a strip. In some implementations, the strip can include subpixels arranged in pairs, each subpixel being i / 6th the width of the pixel pitch and equal to the pixel pitch in length.

[0150] Figures 8A-8B illustrate cross-sections of the optical system having an astigmatic phase mask, which can be one example implementation of the optical layer 810. The phase mask can refer to a type of the optical layer that modifies the phase of light passing through the optical layer 810.

[0151] Figures 8A-8B provide cross-sectional views of the display system at different planes. In some implementations, a surface 820 represents the exit surface where the light rays exit after being transformed from their initial state to a more controlled and collimated state, providing improved display performance. As an example, the surface 820 can represent a surface where the light exits, when the light is being transformed from a wider divergence solid angle to a narrower divergence solid angle after passing through optical layer 810.

[0152] The light rays originating from the sub-pixels 814 are shown with their initial divergence angles 0ps, indicating the angular spread of the light emitted by the sub-pixel 814. The initial divergence angles 0ps shown in Figure 11A representthe angular spread of the light emitted by the sub-pixels 814 when the light enters the optical layer 810. The initial divergence solid angles can lead to several visual artifacts and performance limitations in display systems. For example, large divergence solid angles can result in crosstalk between the adjacent sub-pixels 814, causing the undesired color mixing between the sub-pixels 814 having different colors and reducing the overall image quality. Additionally, the inefficient divergence of light can contribute to the screen door effect, where the boundaries between individual sub-pixels 814 become visible, degrading the perceived resolution and immersion.

[0153] Astigmatism can occur when the light rays from different planes focus at different distances. The astigmatic phase mask can be configured to address astigmatism, e.g., by managing the asymmetric divergence of light rays in orthogonal directions along the XY plane.

[0154] In Figures 8A-8B, the light rays entering the optical layer 810 have the initial divergence angle 0ps in the sagittal (x) plane and the initial divergence angle 0pt in the tangential (y) plane. The optical layer 810 can be configured with surface profiles or microstructures that introduce a phase delay to the incoming light rays. By configuring the optical layer 810, the wavefront of the light can be manipulated to control propagation of the light.

[0155] As the light rays pass through the optical layer 810, the light rays experience different phase delays depending at least partially on their position and angle of incidence. The phase manipulation results in a modification of the divergence solid angles in the sagittal and tangential planes. The surface 820 represents the surface at which the light rays exit to the narrower exit divergence angles 0es / 2 and 0et / 2 in comparison to the wider initial divergence angles 0ps and 0pt. By decreasing the angular spread of the light rays, the optical layer 810 can reduce divergence solid angle of the display system.

[0156] The relationship between the initial divergence angles 0ps and 0pt and the exit divergence angles 0es / 2 and 0et / 2 is described below. The optical layer 810 introduces a phase function cp(x, y) that modifies the wavefront of the light. The phase function is configured to reduce the divergence solid angles in the sagittal and tangential planes.

[0157] The exit divergence angles 0es / 2 and 0et / 2 are related to the initial divergence angles 0ps and 0pt and the phase function cp(x, y) as follows:

[0158] 0es / 2 = f(0ps, cp(x, y)),

[0159] 0et / 2 = g(0pt, (p(x, y)),

[0160] where f and g are functions that at least partially depend on the specific configuration of the optical layer 8io or the optical properties of the optical system.

[0161] The reduction in divergence solid angles achieved by the optical layer 8io provides at least partial mitigation of the screen door effect and improves the visual quality of the display. By condensing the light rays and reducing the angular spread, the optical layer 8io facilitates filling the gaps between sub-pixels 814 and creates a relatively seamless and immersive viewing experience.

[0162] Figures 8A-8B illustrate how the reduced divergence angles 0es / 2 and 0et / 2 achieved by the optical layer 810 having the combined RGB emission surface 820 contribute to the overall improvement of the display visual quality.As an example, after passing through the optical layer 810 at the surface 820, the light rays from the sub-pixels 814 exhibit reduced divergence angles 0es / 2 and 0et / 2 in the sagittal and tangential planes, respectively. These reduced divergence solid angles are at least partially a result of the phase manipulation introduced by the optical layer 810, which collimates the light and reduces the angular spread of the light emitted by each subpixel 814.

[0163] The reduced divergence solid angles have an impact on the light propagation and the formation of the combined RGB emission surface 820. As the light rays from the red, green, and blue sub-pixels 8i4r, 814g, and 814b, respectively, exit the optical layer 810, they converge and overlap, creating a new emission surface 820 where the lights of the different subpixels 814 having the same color blend together relatively seamlessly.

[0164] By reducing the divergence angles 0es / 2 and 0et / 2, the optical layer 810 provides the light from adjacent sub-pixels 814 blending together relatively smoothly, creating a more continuous and uniform emission surface 820.

[0165] In some implementations, the device 800 can include the subpixels 814 arranged in pairs, each subpixel being i / 6th the width of the pixel pitch and equal to the pixel pitch in length, as illustrated in the microscopic picture (see Figure 7). Such configuration provides condensation of the exit angle cone as follows:

[0166] 0et 0pt / 2,

[0167] 9es « 0ps / 6.

[0168] For a square overall pitch, the relationship can be expressed as 9es » 9et. In some implementations, the astigmatic display with varying light cone angles can be transformed into a display with a relatively uniform cone angle.

[0169] The extent of the divergence solid angle reduction and the quality of the combined RGB emission surface 820 can be quantified using various metrics. One such metric is the angular full-width at half-maximum (FWHM), which measures the angular width of the light beam at half of its maximum intensity. A lower FWHM indicates a more collimated and focused light beam, leading to better color mixing and reduced crosstalk between the sub-pixels 814.

[0170] Another metric is the modulation transfer function (MTF), which describes ability of the optical system to transfer contrast from the object (e.g., sub-pixels 814) to the image (e.g., the combined RGB emission surface 820). A higher MTF indicates better image quality, with sharper edges and reduced blurring.

[0171] The improvement in display quality achieved by the optical system can be expressed using such metrics. For example, FWHM of the light beam after passing through the optical layer 810 can be calculated as:

[0172] FWHMes = 2 x arctan(0es / 2),

[0173] FWHMet = 2 x arctan(9et / 2),

[0174] where FWHMes and FWHMet represent the angular full-width at halfmaximum in the sagittal and tangential planes, respectively.

[0175] In some implementations, the MTF of the optical system can be determined by considering the spatial frequency response of the optical layer 810 and the sub-pixel arrangement. The MTF is a function of the spatial frequency f and can be expressed as:

[0176] MTF(f) = |OTF(f)|,

[0177] where OTF(f) is the optical transfer function, which can be the Fourier transform of the point spread function (PSF) of the optical system.

[0178] Figures 8A-8B illustrate divergence solid angle reduction and divergence solid angle control achieved by the optical layer 810. The resulting combined RGB emission surface 820 can provide the reduced screen door effect and improved color mixing. By configuring the optical layer 810 and controlling the divergence solid angles, the optical system can provide high-quality,immersive displays with reduced visual artifacts and improved user experience. The device 800 with the optical layer 810 can be used in various display technologies, including LCDs, OLEDs, and micro-LEDs, improving their display performance.

[0179] The device 800 illustrated in Figures 8A-8B can improve performance of high-resolution displays by reducing the screen door effect and improving optical efficiency due to high etendue. By incorporating the optical layer 810 with nanostructured patterns, the device 800 of the present disclosure can expand the subpixel illumination areas, reduce the exit divergence solid angles, and create a relatively seamless overlapping illumination pattern. The device 800 can reduce the visibility of subpixel boundaries, improve color mixing, and improve the overall display quality.

[0180] Figure 9A illustrates light rays diverging from sub-pixel sources 914. The diagram depicts a state of the light rays without passing through the optical components of the present disclosure. The display panel can include a plurality of subpixels 914b, 914g, and 9i4r, each subpixel 914b, 914g, and 9i4r emitting light of a specific color. The subpixels 914b, 914g, and 9i4r can create the full spectrum of colors that can be appropriate for displaying images and content on the display screen. In Figure 9A, the subpixels 914 can be overlaid by a diffuser that can be a typical diffuser without the optical layer 910 shown in Figure 9B. The typical diffuser can spread light in various directions, which can lead to a loss of intensity and control over the emitted light. Without the optical layer 910 (see Figure 9B) to direct and focus the light, the diffusion process of the typical diffuser may result in a less precise and less efficient distribution of light across the display panel.

[0181] Figure 9B illustrates a device 900 that includes an optical layer 910 to manipulate light in a display system, providing an improvement over the typical diffuser approach (illustrated in Figure 9A) that does not use the optical layer 910. In some implementations, the optical layer 910 redirects the light beams to create a relatively uniform illumination pattern with reduced divergence. Such targeted light manipulation improves the display performance and reduces the negative impact of light scattering.

[0182] Figure 9B illustrates the optical layer 910 redirecting light beams to create a relatively uniform illumination pattern with reduced divergence,improving display performance and at least partially overcoming the limitations associated with the typical diffusers (see Figure 9A) that do not have the optical layer 910. By redirecting light beams and creating a relatively uniform illumination pattern with reduced divergence, the optical layer 910 improves display performance, improves color accuracy, and reduces the impact of light scattering. The nanoscale elements within the optical layer 910 provide targeted light manipulation, offering benefits such as reduced crosstalk between the subpixels 914, improved contrast, and configuration flexibility. The device 900 having the optical layer 910 provides higher-quality, more immersive, and visually appealing display systems.

[0183] In some implementations, the optical layer 910 can include two sublayers: abeam steering sublayer 911 (or flat lens 1) and a reverse color routing sublayer 912 (or flat lens 2). These sublayers can include nano structured patterns that modulate the phase of light to achieve improved beam expansion and divergence solid angle reduction. The spatial variation of the nanostructured patterns provides a relative control over the light propagation through the optical layer 910.

[0184] In some implementations, distribution of permittivity £r (subsequently described in Figures 11B-11C) can be configured to achieve color routing, where wavelengths of light (corresponding to different colors) are selectively directed from their designated subpixels 914. The permittivity distribution 8r of the optical layer 910 can have a spatial variation of permittivity Crto provide control over light propagation.

[0185] By configuring the spatial variation of permittivity er, the wavelengthdependent phase shifts can be achieved to route the red, green, and blue light components from their respective subpixels 9i4r, 914g, and 914b, providing accurate color reproduction and reduced crosstalk. As an example, through the use of silicon dioxide and silicon nitride, the permittivity distribution within the optical layer 910 can provide beam steering and color routing.

[0186] Figure 9B depicts an optical system for a display panel that includes an off-center lens and a symmetric lens. In the example embodiment illustrated in Figure 9B, the off-center lens, which can be disposed over the subpixels 914b and 9i4r having blue and red colors, respectively; the symmetric lens can be disposed over the green subpixel 914g.

[0187] The off-center lens can be configured to steer the light beams from the blue and red subpixels 914b and 9i4r, respectively, according to the appropriate angles. The off-center lens configuration is not centrally aligned with the subpixel light emission axis. For the blue subpixel 914b, the off-center lens can redirect the light beam toward one side, which could be either left or right depending at least partially on the configuration and the appropriate light path. In the embodiment illustrated in Figure 9B, for the red subpixel 9i4r, the off-center lens can direct the light beam toward the opposite side of the blue subpixel 914b. In some implementations, the light from both blue and red subpixels 914b and 9i4r, respectively, is steered in a manner that provides effective color mixing and routing. The off-center lenses for the blue and red subpixels 914b and 9i4r, respectively, can achieve the appropriate overlap of light beams and facilitate the consolidation of etendue and the mitigation of the screen door effect.

[0188] In Figure 9B, the symmetric lens is configured for the green subpixel 914g and is configured to maintain the symmetry of the light beam propagation. The symmetric lens can be substantially aligned with the central axis of light emission of the green subpixel 914g, providing the light beam that remains substantially centered as the light beam passes through the symmetric lens. The symmetric lens provides the light from the green subpixel 914g that is not steered to either the left or right side and that continues to propagate in a direction that is substantially orthogonal to the main surface of the display device 900. The symmetric lens for the green subpixel 914g is beneficial for substantially maintaining the uniformity and consistency of the light output.

[0189] Figure 9B illustrates the use of the off-center and / or symmetric lenses within the optical layer 310 to manipulate the light emitted from the RGB subpixels 914. The off-center lens for the blue and red subpixels 914b and 9i4r, respectively, and the symmetric lens for the green subpixel 914g can control the direction and substantial symmetry of the light beams, contributing to the overall improvement in display performance by reducing the screen door effect and improving color mixing.

[0190] The typical diffuser (see Figure 9A) not using the optical layer 910 scatters light in mostly all directions. In some implementations, the optical layer 910 can control the propagation of light. As an example, the optical layer 910 can have aconfiguration of nanoscale elements, such as flat lenses or photonic crystals, to selectively manipulate the direction and distribution of light.

[0191] The nanoscale elements within the optical layer 910 can be configured to achieve improved light redirection and beam shaping. Such nanoscale elements can be configured to have geometric properties, such as shape, size, and orientation, which interact with the incident light in a controlled manner. By adjusting the properties of the nanoscale elements, the optical layer 910 can steer the light beams toward the improved directions and reduce scattering and divergence that may be inappropriate.

[0192] In some implementations, the optical layer 910 can create a relatively uniform illumination pattern. Typical diffusers (see Figure 9A) without the optical layer 910 can suffer from non-uniformity of the illumination pattern, resulting in visible hot spots or dark regions across the display surface. In some implementations, the optical layer 910 can redistribute the light more evenly, providing the a relatively steady amount of illumination from the pixels. This uniform illumination improves the overall display quality, improving brightness uniformity and reducing the appearance of visual artifacts.

[0193] By configuring the nanoscale elements, the optical layer 910 can collimate the light, reducing its angular spread and focusing the light toward the appropriate direction. Such targeted light manipulation reduces the amount of light that is scattered in unintended directions that maybe not appropriate.

[0194] The reduced divergence achieved by the optical layer 910 has several benefits for display performance. For example, the reduced divergence can reduce the crosstalk between adjacent pixels, providing that the light from the pixel is properly confined within its designated area. The reduction in crosstalk improves the clarity and sharpness of the displayed image, as the individual pixels remain relatively distinct and well-defined.

[0195] In some implementations, the reduced divergence provides maintenance of integrity for the displayed colors. In a typical diffuser-based system without the optical layer 910, the scattered light from the subpixels 914 having different colors can mix and interfere with each other, leading to color desaturation and inaccurate color reproduction. The optical layer 910, with its light redirectioncapabilities, preserves a relative chromatic purity of the color channels, providing that the displayed colors remain relatively vibrant and true to their intended values.

[0196] In some implementations, the controlled divergence of the optical layer 910 contributes to an improved viewing experience, e.g., in terms of contrast and black level performance. By reducing the amount of light that reaches unintended areas of the display, the optical layer 910 can maintain deep and dark black levels, improving the overall contrast ratio of the display. Such improved contrast results in a more immersive and visually appealing image, with better depth perception and increased dynamic range.

[0197] From a manufacturing perspective, the optical layer 910 provides several advantages over the typical diffusers without the optical layer 910. The nanoscale elements within the optical layer 910 can be fabricated using improved lithographic techniques, such as electron beam lithography and nanoimprint lithography, which provide control over the dimensions and arrangement of the elements. The fabrication process provides relative uniformity and reliability of the optical layer 910, allowing for large-scale production with reduced variations in performance.

[0198] In some implementations, the optical layer 910 can be integrated into existing display architectures without substantial modifications to the underlying pixel structure or driving electronics. As an example, the optical layer 910 can be fabricated as a separate component and subsequently laminated or bonded onto the display panel, making the device 900 compatible with various display technologies, such as LCDs, OLEDs, or micro-LEDs.

[0199] The optical layer 910 provides configuration flexibility and customization possibilities. By adjusting the properties of the nanoscale elements, such as their shape, size, and arrangement, the optical layer 910 can be modified to meet specific display criteria and improve performance for different applications. Such adaptability allows for the development of optical layers 910 for various display systems, such as virtual reality headsets, augmented reality glasses, and high- dynamic-range displays.

[0200] A reference is now made to typical color routing systems. A cross-section of the typical color router can include microlenses (MLs) and color filters (CFs) for red, green, blue, and near-infrared (NIR) channels. Beneath the CFs, a thin passivation layer and silicon photodetector (PD) regions can be located. In another typical color router MLs and CFs can be replaced with a color router device. The color router device can route light based on the color of the light directly to PDs, without free-space propagation. Such color routing can provide efficient color routing for subwavelength pixels.

[0201] The color router system can include the color router device with four color channels (RGB-IR, where IR refers to an infrared spectral range) covering both visible and NIR spectral ranges. The color router system can be configured for 400 nm wide pixels with 280 nm wide PDs, the color router device can direct spectral colors to the RGB-IR channel photodetectors substantially without crosstalk, reflections, or light leakage into non-PD regions.

[0202] Atypical color-sorting metalens system for high-sensitivity image sensors with the color router device can include single-layer splitters, which can exhibit averaged sorting efficiencies of up to 51 percent, accommodate acceptable angles of up to 16.5 degrees or 0.068 steradian, and support pixel sizes down to submicrometer levels.

[0203] In a typical color image sensor configuration without the color router device, not more than approximately 25 percent of the incident light can reach the photodetectors. A color image sensor employing on-chip color splitters using the color router device can have substantially all incident light reaching the photodetectors.

[0204] Atypical color-sorting metalens array for an image sensor application can include functionalities of a color splitter and a lens and can be directly integrated into sensor pixels. An operation of the metalens array can provide sorting substantially all incident light and focusing such light into four separate pixels based on the color of the light.

[0205] Figures 10A-10C illustrate a color router that can route lights of different wavelengths to appropriate channels. Figure 15A presents a light field profile for blue light at a wavelength of 457 nm as it passes through an RGB router. The fieldprofile in Figure 10A illustrates the intensity distribution of the blue light. The RGB router is configured to selectively direct light based on color, routing each color light to an appropriate channel. The router can maintain a relative purity and intensity of the blue channel.

[0206] Figure 10B shows a light field profile for green light at a wavelength of 527 nm in the RGB router. Similar to the blue light, the green light is manipulated by the RGB router to steer the light towards the appropriate path. The field profile indicates a relatively strong and focused intensity distribution for the green light.

[0207] Figure 10C depicts a light field profile for red light at a wavelength of 611 nm as it passes through the RGB router. The router can steer the red light to an appropriate channel. The field profile for the red light shows a concentrated intensity distribution, indicating that the router can substantially preserve the color integrity and brightness of the red color.

[0208] Figure 11A depicts a top view of a display panel illustrating an array of RGB subpixels 1114. Figure 11A shows the dimensions and arrangement of RGB subpixels 1114b, 1114g, and ni4r in the display panel 1100 having a plurality of pixels 1102. The optical layer 1110 is configured to accommodate the dimensions, with the pixel 1102 having a pitch of 4.5pm x 4.5pm. In some implementations, all subpixels 1114 can have a width of 1pm and the width-wise distance between each subpixel being 0.5pm, while all subpixels 1114 can have a length of 3pm.

[0209] The optical layer 1110, which overlays the subpixels 1114, is configured to accommodate the subpixel dimensions. The optical layer 1110 can expand the light emitted from the subpixel 1114 to cover the full area corresponding to a pixel pitch. The optical layer 1110 can mix the emitted colors, thereby improving the color uniformity and vibrancy of the displayed image. In some implementations, the optical layer 1110 can reduce the visible gaps between subpixels 1114, which are perceived as a grid-like pattern of the screen door effect. By reducing the visible gaps, the optical layer 1110 improves the visual appeal of the display and contributes to a more immersive viewing experience.

[0210] The configuration of the subpixels 1114 shown in Figure 11A provides the light from the subpixels 1114 to be manipulated effectively, resulting in a display panel that provides higher resolution, accurate color reproduction, and reducedvisual artifacts. The combination of the subpixel arrangement and the optical layer 1110 can improve the high-resolution displays.

[0211] Figures 11B-11C depict the permittivity distribution Er of the material for the optical layer mo at different cross-sections in the XZ and XY planes. The spatial variation of permittivity £r controls at least partially the phase modulation of light.

[0212] Permittivity Er is a property of materials that describes ability of the materials to store and transmit electromagnetic energy. The permittivity Er is a measure of how efficiently a material can be polarized by an electric field. The distribution of permittivity srcontrols at least partially the propagation of light through the material. The distribution of permittivity Er within the optical layer 1110 determines how light interacts with the material of the optical layer mo and how the light is modified as the light passes through the material.

[0213] The distribution of permittivity e> allows for control at least partially over the light propagation through the optical layer nio. The optical layer mo can include a mixture of silicon dioxide (Si02) with a relative permittivity srof two (2) and silicon nitride (SiN) with a relative permittivity 8rof four (4).

[0214] Figures 11B and 11C illustrate the internal structure and properties of the optical layer 1110. More specifically, Figures 11B and 11C illustrate the distribution of permittivity £rin the optical layer 1110, showing the spatial variation of permittivity Erin different cross-sections. Figures 11B and 11C depict the distribution of the permittivity £1 of the optical layer 1110 material at crosssections along the XZ and XY planes.

[0215] In some implementations, the optical layer 1110 having the different distribution of the permittivity Er can manipulate light propagation and achieves the improved beam steering or reverse color routing effects. As an example, by configuring the spatial variation of permittivity Er in the material, the optical layer 1110 can control the phase and amplitude of the light waves as the light waves propagate through the optical layer 1110. Such control of the light properties provides the manipulation of the light beams emitted by the subpixels 1114.

[0216] Figure 11B depicts the distribution of permittivity Erin the XZ plane of the optical layer 1110. More specifically, the cross-sectional view in the XZ planeillustrates the spatial variation of permittivity Er along the horizontal (X) and vertical (Z) axes. The different shades or colors in Figures 11B-11C represent different values of permittivity er, with different value of permittivity srcorresponding to a specific material composition.

[0217] Figure 11C illustrates the distribution of permittivity Erin the XY plane of the optical layer 1110. The cross-sectional view in the XY plane illustrates the spatial variation of permittivity Er along the horizontal (X) and depth (Y) axes. The different shades or colors represent different permittivity values, indicating the presence of different materials or material compositions.

[0218] The spatial variation of permittivity erwithin the optical layer 1110 is achieved by combining different materials with distinct permittivity values. In the present disclosure, the optical layer 1110 can include a mixture of silicon dioxide (SiO2) and silicon nitride (SiN). Silicon dioxide has a relative permittivity Er of approximately two (2), while silicon nitride has a relative permittivity srof around four (4). By arranging these materials within the optical layer 1110, the permittivity distribution can be configured in such a way that the distribution of permittivity Er provides the appropriate phase modulation of light.

[0219] In some implementations, a surface 1120 represents the surface where the light exits, such that the light is transformed from a wider divergence solid angle to a narrower divergence solid angle after passing through the optical layer 1110. In some implementations, a variation in height of the surface 1120 of the optical layer 1110 can be a difference between a relatively high profile of the material (e.g., nanostructured patterns of silicon dioxide and silicon nitride) of the optical layer 1110 and a relatively low profile of such material. The variation in height of the surface 1120 can be, for example, equal or less than 1.5 micron.

[0220] The phase modulation of light can provide beam steering or reverse color routing. As light propagates through the optical layer 1110, it is transformed by different phase shifts depending at least partially on the local permittivity value. These phase shifts can be configured to provide constructive or destructive interference patterns, effectively redirecting the light in the appropriate directions or selectively transmitting or reflecting the wavelengths.

[0221] For example, by configuring the distribution of permittivity erthat can introduce a linear phase gradient across the optical layer mo, the light beam can be steered in the appropriate direction. Such beam steering capability is beneficial for directing the expanded illumination from the subpixel 1114 to cover the full pixel pitch.

[0222] In some implementations, the distribution of permittivity ercan be configured to achieve reverse color routing, where wavelengths of light (corresponding to different colors) are selectively directed from their designated subpixels 1114. By configuring the spatial variation of permittivity er, the wavelength-dependent phase shifts that reversely route the red, green, and blue light components from their respective subpixels 1114 can be configured.

[0223] The distribution of permittivity e, in the optical layer 1110 provides at least partial control over the light propagation, providing the improved beam steering or reverse color routing functionalities. By selecting the materials and their spatial arrangement, the optical layer 1110 can reduce the screen door effect.

[0224] In some implementations, fabrication of the optical layer 1110 with the improved permittivity distribution can include computational modeling and nanofabrication techniques. The selection of materials, such as silicon dioxide and silicon nitride, can be based on optical properties of such materials, compatibility with existing manufacturing processes, or ability to provide the improved permittivity distribution.

[0225] In some implementations, the use of silicon dioxide and silicon nitride in the optical layer 1110 provides several advantages. As an example, such materials exhibit low optical losses, high transparency, and appropriate thermal and mechanical stability, making such materials suitable for integration into display systems. In some implementations, the relatively straightforward fabrication processes for such materials can provide a scalable production of the optical layer 1110.

[0226] Figures 11B and 11C illustrate that by configuring the distribution of permittivity 8r, the improved beam steering or reverse color routing can be achieved, improving the performance of the display system.

[0227] Figures 12A-12C present cross-sectional views of near-field radiation patterns for blue, green, and red light beams 1218, 1220, and 1222, respectively. The simulations were performed using the finite-difference time-domain (FDTD) method. The FDTD method is a computational technique for modeling electromagnetic wave interactions with material structures.

[0228] The near-field can refer to the region close to an object or source where the electromagnetic fields are dominant. In some implementations, the near-field region can be within a few wavelengths of the source, where the electric and magnetic fields are not fully separated and behave akin to a combined electromagnetic field. The near-field region can have relatively non-uniform field distribution and relatively significant interactions between the fields and nearby objects.

[0229] The vertical scale in each Figure 12A-12C depicts the energy or power profile that occurs when the power, defined as the square of the intensity, decreases to half of its peak value at the center of the cross-sectional view.

[0230] The near-field distribution of light from the individual blue, green, and red subpixels 1214b, 1214g, and 12141, respectively, is illustrated separately in Figures 12A, 12B, and 12C, respectively. The near-field simulation used the following wavelengths: blue at 457nm, green at 52ynm, and red at 6nnm. Each subpixel 1214 represented a ipm x 3qm cross-section waveguide, and the zeroth (oth) order waveguide mode was used in the simulation.

[0231] Figures 12A-12C illustrate the relatively large divergence solid angles that can lead to several visual artifacts and performance limitations in display systems. As illustrated in Figure 12A for the blue light without using the flat lens optical layer 1310 (see Figures 13A-13C), the cone angle was around 30-35 degrees (or 0.226 to 0.304 steradian). For the green light illustrated in Figure 12B, the cone angle was around 40 degrees or 0.394 steradian. For the red light illustrated in Figure 12C, the cone angle was approximately 40 degrees or 0.394 steradian.

[0232] The cone angles for Figures 12A-12C (the device without the optical layer 1310) were greater than for the device 1300 using the flat lens optical layer 1310 (see Figures 12D-12F) indicating a greater divergence of the light beams 1218,1220, and 1222 in Figures 12A-12C. The large divergence solid angles can result in crosstalk between the adjacent sub-pixels 1214, causing the undesired color mixing between the sub-pixels 1214 having different colors and reducing the overall image quality.

[0233] Figures 13A-13C present near-field simulation results of light propagation through the display system with the optical layer 1310. In the FDTD method, the subpixel was treated as a ipm x 3pm cross-section waveguide. The zeroth (oth) order waveguide mode was launched in the simulations. The near-field profiles demonstrate color separation and beam shaping by the optical layer 1310 for blue (457nm), green (527nm), and red (6nnm) wavelengths of a blue color beam 1318, a green color beam 1320, and a red color beam 1322, respectively. The relatively well-defined intensity distributions indicate that the optical layer 1310 can steer light beams 1318, 1320, and 1322 from the subpixels 1314b, 1314g, and 13141, respectively to their designated areas.

[0234] Figure 13A presents a near-field simulation result of light propagation through the display system with the optical layer 1310 for the blue color channel at a wavelength of 457 nm. The simulation was performed using the FDTD method. In the FDTD simulation, the subpixel 1314 was treated as a 1pm x 3qm cross-section waveguide. The waveguide representation allows for modeling of the light emission from the subpixels 1314 and their interaction with the optical layer 1310. The simulation in Figure 13A illustrates the blue color channel achieving color reproduction and reducing the screen door effect.

[0235] The near-field profile represents the electromagnetic field distribution in relatively close proximity to the optical layer 1310 and illustrates how the light is manipulated and shaped by the nanostructures within the optical layer 1310.

[0236] The configured nanostructures within the optical layer 1310, which include a mixture of silicon dioxide (SiO2) and silicon nitride (SiN) as described herein, modulate the phase and amplitude of the blue light as it passes through the optical layer 1310. By modifying the permittivity distribution and the arrangement of the silicon dioxide and silicon nitride materials, the improved light manipulation and color reproduction characteristics can be achieved.

[0237] The vertical scale in each Figure 13A-13C depicts the energy when the power decreases to half of its peak value at the center of the cross-sectional view. Within the divergence solid angle corresponding to the power decreased to half of its peak, the power profile encompasses approximately 40% of the total energy.

[0238] The near-field profile in Figure 13A shows a relatively defined and concentrated light distribution having a divergence solid angle equal or less than 0.024 steradian or five degrees for the half angle (or 10 degrees in a full angle in linear length) when the value of energy within the cone includes over 40% of the total energy. Such relatively defined and concentrated light distribution indicates that the optical layer 1310 shapes and directs the blue light in the appropriate direction. The spatial confinement of the light can be beneficial for reducing crosstalk between adjacent subpixels 1314 and improving the overall display quality.

[0239] In some implementations, the near-field profile in Figure 13A differs from the light propagation without the presence of the optical layer 1310 (see Figure 12A). As an example, without the meta-lens or flat lens structure, the blue light emitted from the subpixel 1214b can diverge at a larger angle, resulting in a more diffused and less controlled light distribution. Figure 13A illustrates the improvement in light manipulation and confinement achieved by the optical layer 1310.

[0240] Figures 13B and 13C present near-field simulation results of the green and red light propagation, respectively, through the optical layer 1310 at wavelengths of 527 nm and 611 nm. Similar to Figure 13A, which focuses on the blue color channel, Figure 13B-13C demonstrate the effectiveness of the optical layer 1310 in controlling and shaping the green and red light propagation. As an example, Figures 13B-13C show relatively defined and concentrated light distribution having divergence solid angles equal or less than 0.024 steradian or five degrees for the half angle (or ten degrees in a full angle in linear length) when the value of energy within the cone includes over 40% of the total energy.

[0241] The simulations, performed using the FDTD method, demonstrate the effectiveness of the optical layer 1310 in manipulating and shaping the green and red light, leading to defined and concentrated light distributions. In some implementations, the optical layer 1310 can provide advantages such as, forexample, reducing the screen door effect, improving color mixing, and improving optical efficiency for all three color channels. In some implementations, the optical layer 1310 may provide high-quality, full-color displays with reduced visual artifacts across relatively the entire RGB color spectrum.

[0242] The near-field simulation results presented in Figures 13A-13C demonstrate the effectiveness of the optical layer 1310 over the display devices without the optical layer 1310 (see Figures 12A-12C). The flat lens structure, with the appropriate nanostructures and permittivity distribution, can provide at least a partial control over the light propagation for all three color channels, resulting in improved display quality, reduced screen door effect, and improved optical efficiency.

[0243] In some implementations, the optical layer 1310 with meta-lens or flat lens structure can provide advantages for all three color channels - blue, green, and red - over the micro-concentrator and or micro-lens layers described herein. The display devices without the optical layer 1310 may have limitations such as visible subpixel boundaries, limited color mixing, and reduced optical efficiency. The optical layer 1310 achieves a reduction of the screen door effect by expanding the illumination area, reducing the divergence solid angle, and providing color mixing for the color channel.

[0244] Figures 14A-14C display the far-field radiation patterns for the blue, green, and red light beams 1418, 1420, and 1422, respectively, without using the optical layer 1310. Figures 15A-15C illustrate the light distribution achieved by the optical layer 1310. More specifically, Figures 15A-15C display the corresponding far-field radiation patterns for the blue, green, and red light beams 1518, 1520, and 1522, respectively, after passing through the optical layer 1310.

[0245] Without the optical layer 1310, the far-field patterns illustrated in Figures 14A-14C exhibit elliptical beams 1418, 1420, and 1422 with 40 degrees by seventeen degrees of divergence angles. The display devices not using the optical layer 1310 may suffer from limitations such as visible subpixel boundaries, limited color mixing, and reduced optical efficiency due to the larger divergence solid angles and less controlled light distribution.

[0246] In some implementations, the far field can refer to a region that is disposed at a distance of 10mm or more away from the panel surfaces. In the far- field region, the electromagnetic waves or fields are considered to be sufficiently far from the panel. In some implementations, the waves in the far-field region can have a relatively uniform wavefront and directionality, providing more predictable and consistent behavior compared to the near field.

[0247] In some implementations, the far-field patterns using the optical layer 1310 (see Figures 15A-15C) show relatively circular beams 1518, 1520, and 1522 with reduced divergence solid angles. In some implementations, the divergence angle of each subpixel 1314 can be equal to or less than half angle of five degrees (equivalent to a full angle of ten degrees in linear measurement) corresponding to a solid angle of 0.024 steradian measured at a distance of 20 mm from a top surface of the subpixels 1314. This reduction in divergence solid angle provides the mitigation of the screen door effect and improves the overall display quality.

[0248] Figure 15A presents a far-field radiation pattern for the blue color channel at a wavelength of 457 nm, demonstrating the light distribution after passing through the optical layer 1310. Figure 15A illustrates the angular distribution and divergence of the blue light.

[0249] The far-field radiation pattern in Figure 15A is represented in a polar coordinate system, with the radial distance indicating the intensity of the light and the angular position representing the direction of propagation. The pattern shows a concentrated or collimated beam 1518 of the blue light, with a reduced divergence solid angle compared to the light distribution without the optical layer 1310 (see Figure 14A).

[0250] In some implementations, the optical layer 1310 transforms the blue light distribution such that the far-field radiation pattern of the device 1300 having the optical layer 1310 (Figure 15A) is improved in comparison to the display device without the meta-lens or flat lens structure. As an example, when the flat lens are not used, the blue light emitted from the subpixels 1314 can exhibit a wider divergence angle, approximately 40 degrees by seventeen degrees, resulting in a more diffused and less controlled light distribution. The elliptical shape of the beam 1418 without the optical layer 1310 indicates that the light is not well-collimated and spreads more in the horizontal direction than the vertical direction.

[0251] In some implementations, the far-field radiation pattern in Figure 15A, illustrates that the blue light beam 1518 is concentrated and substantially circular in shape, e.g., for intensity of 0.004 (comparing the relative strength of the light at different angles in the polar plot illustrated in Figure 15A), with a reduced divergence angle with five degrees for a half angle (or ten degrees for a full angle) or 0.024 steradian solid angle. Such reduction in divergence solid angle can be a result of the configured nanostructures and / or permittivity distribution of the optical layer 1310.

[0252] In some implementations, the cross-section profile of the blue beam 1518 in the far-field can be at least partially elliptical having a ratio of a longer diameter of the beam profile to a lower diameter of the beam profile being in a range between one and 1.5. In some implementations, green and red color beams 1520 and 1522, respectively (see Figures 15B-15C, respectively) can provide similar partially elliptical profiles having the ratio of 1.5.

[0253] In some implementations, reducing the divergence solid angle in mitigating the screen door effect can improve the overall display quality. As an example, by collimating the blue light and reducing its angular spread, the optical layer 1310 provides the light from the subpixel 1314 that is efficiently directed toward the viewer eye, reducing undesired crosstalk between adjacent sub pixels 1314 and improving the perceived image quality.

[0254] The optical layer 1310, having meta-lens or flat lens structure, achieves the reduction in divergence solid angle through phase modulation and wavefront shaping. As mentioned above, the optical layer 1310 includes a mixture of silicon dioxide (Si02) and silicon nitride (SiN), arranged in a pattern to create a permittivity distribution. Such permittivity distribution allows for the manipulation of the phase and amplitude of the blue light as it propagates through the optical layer 1310, resulting in the collimated and relatively concentrated far-field radiation pattern observed in Figure 15A.

[0255] The far-field radiation pattern in Figure 15A demonstrates the effectiveness of the optical layer 1310 over the display devices without the opticallayer 1310 (see Figure 14A). As an example, the optical layer 1310 can control the light distribution, reduce divergence solid angles, and improve display performance. Such improved light manipulation by the optical layer 1310 can provide reduced visual artifacts.

[0256] The far-held radiation patterns in Figure 15A of the device 1300 having the optical layer 1310 provides improvement over the far-held radiation patterns provided by a display device not using the optical layer 1310 (such as the display device using the micro-concentrators or micro-lenses described herein). As an example, the far-held radiation pattern in Figure 15A shows one of the advantageous results of combining and aligning the RGB light from the subpixels 1314 to achieve a relatively seamless and uniform display appearance.

[0257] The far-held radiation pattern in Figure 15A illustrates controlling the blue light distribution by the optical layer 1310. In some implementations, the optical layer 1310, with the hat lens structure, achieves a relatively collimated and concentrated blue light beam 1518, as demonstrated by the far-field radiation pattern in Figure 15A. The concentrated and collimated beam 1518 indicates that a portion of the blue light is effectively captured and directed, reducing optical losses.

[0258] In some implementations, the optical layer 1310 can reduce the screen door effect, improve color mixing, and improve overall display quality. The permittivity distribution within the optical layer 1310, including of silicon dioxide and silicon nitride, allows for phase modulation and wavefront shaping, resulting in the collimated and concentrated blue light beam 1518 observed in Figure 15A.

[0259] Figures 15B and 15C present the far-held radiation patterns for the green and red color channels at wavelengths of 527 nm and 611 nm, respectively.Figures 15B-15C present the far-field radiation pattern for the green and red color channels, respectively, illustrating the light distribution after passing through the optical layer 1310.

[0260] In some implementations, the far-held radiation patterns in Figures 15B- 15C illustrate the efficiency of the optical layer 1310 in directing the green and red lights, respectively, toward the viewer eye. As an example, the concentrated and collimated beams 1520 and 1522 in Figures 15B-15C indicate that a portion of thegreen and red lights are effectively captured and directed, reducing optical losses and improving the overall display efficiency.

[0261] In some implementations, the optical layer 1310 can reduce the screen door effect, improve color mixing, and improve overall display quality. The permittivity distribution within the optical layer 1310, consisting of silicon dioxide and silicon nitride, allows for phase modulation and wavefront shaping, resulting in collimated and concentrated light beams 1520 and 1522 for the green and red color channels, as observed in Figures 15B-15C.

[0262] The far-field radiation patterns in Figures 15B-15C demonstrate advantages of the optical layer 1310 over the display devices without the optical layer 1310. As an example, the optical layer 1310 can control the light distribution, reduce divergence solid angles, and improve display performance for green and red color channels. The improved light manipulation can provide high-quality, immersive display systems with reduced visual artifacts across relatively the entire visible spectrum.

[0263] In some implementations, the display device 1300 using the optical layer 1310 with the meta-lens or flat lens structure having the far-field radiation patterns illustrated in Figures 15A-15C provide the reduction in divergence solid angle and the improved light control provided by the optical layer 1310 for all three color channels.

[0264] In some implementations, the display system having the optical layer 1310 can consolidate etendue and reduce the screen door effect without substantially sacrificing resolution. By overlapping the RGB subpixel illumination areas to expand to the full pixel pitch of about 4.5pm, the optical layer 1310 can mix colors while relatively maintaining the original subpixel dimensions. The devices not using the optical layer 1310, for example, the micro-concentrator or micro-lens arrays, can expand illumination to a relatively limited 2 / 3 pixel pitch and still exhibit visible subpixel gaps.

[0265] Under microscopic evaluation with a KEYENCE® VHZ-7000N microscope (supplied by Keyence at 500 Park Boulevard, Suite 200, Itasca, Illinois) and the like microscopes having a resolving power finer than 0.5 microns, the optical layer 1310 provides light emission from relatively the entirepixel area as one spot, rather than showing relatively distinct RGB subpixel emissions. The relatively seamless integration of colors at such microscopic level is achieved by the optical layer 1310 configuration allowing for reduction of the screen door effect.

[0266] In some implementations, combining the RGB light from the subpixels 1314 can provide a full-color display with improved visual quality. The optical layer 1310, with appropriate nanostructures and permittivity distribution, provides the mixing and overlapping of the red, green, and blue lights. By expanding the illumination area of the subpixel and reducing the divergence solid angle, the optical layer 1310 provides the RGB light, which is combined and directed towards the viewer eye, resulting in a high-quality, full-color image.

[0267] In some implementations, the performance of the optical layer 1310 for all color channels using the meta-lens or flat lens structure effectively expands the light from the respective subpixel 1314 to cover the full pixel pitch while simultaneously reducing the divergence solid angle. This expansion and collimation of the light of a specific color subpixel lead to a more uniform and relatively seamless display appearance, reducing the screen door effect.

[0268] In some implementations, the optical layer 1310 with meta-lens or flat lens structure provides advantages over the micro-concentrator or microlens layers described herein. The optical layer 1310 achieves a reduction of the screen door effect by expanding the illumination area, reducing the divergence solid angle, and providing color mixing.

[0269] In some implementations, the flat lens configuration of the optical layer 1310 offers advantages over typical devices that do not use the optical layer 1310. As an example, the optical layer 1310 can include one layer having a thickness of 2pm, which is relatively lightweight and can be integrated into existing display manufacturing processes.

[0270] Figure 16 is a block diagram of a computing system 1600 that may be used for implementing the devices and methods disclosed herein. For example, the computing system can be any component of the display system disclosed herein. Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device.Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 1600 includes a processing unit 1602. The processing unit includes a central processing unit (CPU) 1614, memory 1608, and may further include a mass storage device 1604, a video adapter 1610, and an I / O interface 1612 connected to a bus 1620.

[0271] The bus 1620 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 1614 may comprise any type of electronic data processor. The memory 1608 may comprise any type of non-transitory system memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 1608 may include ROM for use at bootup, and DRAM for program and data storage for use while executing programs.

[0272] The mass storage 1604 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 1620. The mass storage 1604 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

[0273] The video adapter 1610 and the I / O interface 1612 provide interfaces to couple external input and output devices to the processing unit 1602. As illustrated, examples of input and output devices include a display device 1618 coupled to the video adapter 1610 and a mouse, keyboard, or printer 1616 coupled to the I / O interface 1612. The display device 1618 may incorporate and utilize the techniques described in this disclosure. Other devices may be coupled to the processing unit 1602, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) maybe used to provide an interface for an external device.

[0274] The processing unit 1602 also includes one or more network interfaces 1606, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 1606 allow the processing unit 1602 to communicate with remote units via the networks. For example, the network interfaces 1606 may provide wireless communication viaone or more transmitters / transmit antennas and one or more receivers / receive antennas. In an embodiment, the processing unit 1602 is coupled to local-area network(s) 1622 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0275] Figure 17 is a flow chart of a process 1700, according to an example of the present disclosure. In some implementations, one or more process blocks of Figure 17 may be performed by the device 300, 600, 800, 900, 1100, or 1300.

[0276] As shown in Figure 17, process 1700 may include disposing an optical layer over a subpixel of a plurality of subpixels (block 1702). In some implementations, each subpixel of the plurality of subpixels can emit a beam and correspond to a color. As in addition shown in Figure 17, process 1700 may include combining, by the optical layer, the beams of each subpixel of the plurality of subpixels (block 1704). Combining the beams can be performed by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch, as described above.

[0277] As an example, the optical layer 310, 610, 810, 910, 1110, or 1310 can be configured to expand the light from the subpixel 314, 614, 814, 914, 1114, or 1314 to cover an area corresponding to a full pixel pitch. The process can include mixing of light from different color subpixels 314, 614, 814, 914, 1114, or 1314 and the reduction of an exit cone angle of the light. In some implementations, the optical layer 310, 610, 810, 910, 1110, or 1310 provides overlapping illumination and / or reduced divergence solid angle through the use of a flat lens of the present disclosure.

[0278] In some implementations, the present disclosure reduces the visibility of the boundaries between sub-pixels 314, 614, 814, 914, 1114, or 1314 by using the flat lens to mix and overlap the illumination from adjacent sub-pixels 314, 614, 814, 914, 1114, or 1314. As an example, the optical layer 310, 610, 810, 910, 1110, or 1310 can include the flat lens structure that is placed over the subpixels 314, 614, 814, 914, 1114, or 1314 of the display panel. In some implementations, the device 300, 600, 800, 900, 1100, or 1300 may manipulate a divergence solid angle of the combined beams such that the divergence solid angle of the combined beams overlaps at least 80 percent of the divergence solid angle of eachsubpixel of the plurality of subpixels, as described above. In some implementations, the device 300, 600, 800, 900, 1100, or 1300 maybe included in a display panel with optical layer for etendue consolidation and screen door effect mitigation, as described above.

[0279] The method illustrated in Figure 17 can implement the embodiments described in, e.g., Figures 15A-15C, which show the far-field radiation patterns for blue, green, and red light beams 1518, 1520, and 1522, respectively. Figures 15A- 15C demonstrate the effectiveness of the optical layer 310, 610, 810, 910, 1110, or 1310 in producing a relatively concentrated and collimated beam with the reduced divergence solid angle, which is at least partially a result of permittivity distribution of the flat lens of the optical layer 310, 610, 810, 910, 1110, or 1310. In some implementations, the optical layer 310, 610, 810, 910, 1110, or 1310, including a mixture of silicon dioxide (Si02) and silicon nitride (SiN), provides phase modulation and wavefront shaping, as illustrated in Figures 11B-11C.

[0280] Furthermore, the computing system 1600, as shown in Figure 16, may be utilized to implement the device 300, 600, 800, 900, 1100, or 1300, which can manage operation of the optical layer 310, 610, 810, 910, 1110, or 1310. The computing system 1600 includes the CPU 1614, a memory 1608, and interfaces 1612, which facilitate communication with other devices and users, thereby providing the execution of the method depicted in Figure 17.

[0281] In some implementations, the method outlined in Figure 17, in conjunction with the optical layer 310, 610, 810, 910, 1110, or 1310 and the computing system 1600, provides reduction of the screen door effect in display panels.

[0282] It should be noted that while Figure 17 shows example blocks of process 1700, in some implementations, process 1700 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Figure 17. Additionally, or alternatively, two or more of the blocks of process 1700 may be performed in parallel.

[0283] Embodiments may achieve advantages. For example, the present disclosure provides a display device 300, 600, 800, 900, 1100, or isoowith an optical layer 310, 610, 810, 910, 1110, or 1310 that effectively mitigates the screendoor effect, reduces the divergence solid angle, and improves optical efficiency. By expanding subpixel illumination areas, reducing exit divergence solid angles, and creating a relatively seamless overlapping illumination pattern, the device 300, 600, 800, 900, 1100, or isooimproves display quality, color mixing, and overall visual performance. The flat lens approach provides the improvements disclosed herein while maintaining a thin form factor and compatibility with established manufacturing techniques. The technical improvements achieved by the device 300, 600, 800, 900, 1100, or isooprovide the high-resolution displays with superior image quality and viewing experience.

[0284] It should be appreciated that one or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. The respective units / modules maybe hardware, software, or a combination thereof. For instance, one or more of the units / modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0285] Although the description has been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

What is Claimed:

1. A device, comprising: an optical layer configured to be disposed over a subpixel of a plurality of subpixels, each subpixel of the plurality of subpixels emitting a beam and corresponding to a color, wherein the optical layer is configured to at least one of: combine the beams of each subpixel of the plurality of subpixels, or mix the colors of the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch, and wherein an overall divergence solid angle of the combined beams overlaps at least 80 percent of a divergence solid angle of each subpixel of the plurality of sub pixels.

2. The device of Claim i, wherein the combined beams having the overall divergence solid angle comprises at least 50 percent of light energy emitted by each subpixel of the plurality of subpixels.

3. The device of Claim 1, wherein the optical layer is configured to reduce a divergence solid angle of the subpixel to a range between 1 / 3 and 1 / 1000 with respect to a subpixel not having the optical layer disposed over the subpixel.

4. The device of Claim 3, wherein the optical layer is configured to reduce the divergence solid angle of the subpixel to a range between 1 / 6 and 1 / 100 with respect to the subpixel not having the optical layer disposed over the subpixel.

5. The device of Claim 1, wherein a variation in height of a surface of the optical layer is equal or less than 1.5 micron.

6. The device of any of Claims 1-5, wherein the optical layer is configured to: steer a plurality of beams of a first subpixel to a first angle; and steer a first color of the first subpixel to combine beams of the plurality of beams.

7. The device of any of Claims 1-5, wherein: the optical layer comprises a first sublayer and a second sublayer,the first sublayer is configured to steer a plurality of beams of a first beam of a first subpixel to a first angle, and the second sublayer is configured to steer a first color of the first subpixel to combine beams of the plurality of beams.

8. The device of any of Claims 1-6, wherein a cross-section of a beam profile in a far field is at least partially elliptical comprising a ratio of a longer diameter of the beam profile to a lower diameter of the beam profile being in a range between one and 1.5.

9. The device of Claim 1, wherein projections above the optical layer from active subpixels having a first color at least partially overlap.

10. The device of Claim 1, wherein the optical layer is passive.

11. The device of Claim 1, wherein the optical layer comprises an area of an RGB pixel unit.

12. The device of Claim 1, wherein the plurality of subpixels are arranged in a hexagonal pattern.

13. The device of Claim 1, wherein the plurality of subpixels are arranged in a strip pattern.

14. The device of Claim 1, wherein the divergence solid angle of each subpixel of the plurality of subpixels is equal to or less than 0.024 steradian measured at a distance of 20 mm from a top surface of the sub pixels.

15. The device of Claim 1, wherein an area of an RGB pixel unit is covered by a cross-section profile of the beam being viewed by a microscope having a resolve power equal or finer than 0.5 microns.

16. The device of Claim 1, wherein a product of an area of pixels comprising a display panel having a surface area of 590 mm2and an overall divergence solid angle is less than 14 mm2x steradian.

17. A system, comprising: a display device comprising:an optical layer configured to be disposed over a subpixel of a plurality of subpixels, each subpixel of the plurality of subpixels emitting a beam and corresponding to a color, wherein the optical layer is configured to at least one of: combine the beams of each subpixel of the plurality of subpixels, or mix the colors of the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch, and wherein a divergence solid angle of the combined beams overlaps at least 80 percent of a divergence solid angle of each subpixel of the plurality of subpixels.

18. The system of Claim 17, wherein the optical layer is configured to reduce a divergence solid angle from the subpixel to a range between 1 / 3 and 1 / 1000 with respect to a subpixel not having the optical layer over the subpixel.

19. The system of Claim 18, wherein the optical layer is configured to reduce the divergence solid angle of the subpixel to a range between 1 / 6 and 1 / 100 with respect to the subpixel not having the optical layer disposed over the subpixel.

20. A method comprising: disposing an optical layer over a subpixel of a plurality of subpixels, each subpixel of the plurality of subpixels emitting a beam and corresponding to a color, combining, by the optical layer, the beams of each subpixel of the plurality of subpixels by expanding the beam from each subpixel of the plurality of subpixels to cover an area corresponding to a full pixel pitch, wherein a divergence solid angle of the combined beams overlaps at least 80 percent of a divergence solid angle of each subpixel of the plurality of subpixels.

Images