In-vehicle display with stereoscopic and monocular depth programming

Abstract

To provide a display system for use in a vehicle.SOLUTION: A display system configured to be integrated into a vehicle is provided, comprising a light source and an optical subsystem optically coupled to the light source. The optical subsystem includes a reflector and at least one semi-reflective optical member, and is configured to generate light and direct light rays to provide a plurality of virtual images that appear to a viewer concurrently at each of a plurality of different optical depths. Each of the virtual images travels a different distance within the optical subsystem before exiting the optical subsystem on a path toward eyes of the viewer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (Related Applications) This application is a continuation-in-part of U.S. Patent Application No. 17 / 810,567, filed July 1, 2022, and entitled "Display and Imaging Systems with Dynamically Controllable Optical Path Length," which is incorporated by reference in its entirety.

[0002] This is also a continuation-in-part of U.S. patent application Ser. No. 17 / 823,414, filed August 30, 2022, entitled "Full Light Field with Monocular and Stereoscopic Depth Control via Monocular-Binocular Hybridization," and U.S. patent application Ser. No. 17 / 810,567, filed July 1, 2022, entitled "Display and Imaging Systems with Dynamically Controllable Optical Path Length," each of which is incorporated by reference in its entirety into this disclosure.

[0003] This application relates generally to light field displays and imaging devices, and more particularly to dynamically controlling the path of light emitted within a light field display or imaging device to affect the image produced or captured thereby. [Background technology]

[0004] In today's society, advances in electronics and microforming technology are driving an increasing movement toward more immersive light-field and / or autostereoscopic three-dimensional (3D) displays. Most current and common autostereoscopic 3D displays likely require virtual reality (VR) headgear or similar devices. However, VR headgear can cause eye strain and related fatigue issues. These problems are due to two main issues with current and common VR headgear. First, most current and common VR headgear splits the image into two viewing zones, then extracts and overlaps the parallax from these viewing zones to obtain a single overall image. Second, most current and common VR headgear positions the viewing zones too close to the user's eyes. Another issue with current and common VR headgear is that the image is delivered to two separate viewing zones (one for each user's eye) by separate optics, resulting in a binocular gap in the projected image.

[0005] Recent advances in display technology include the use of coaxial light field techniques to create immersive 3D displays with a wide field-of-view (FOV). However, even the latest display technologies face various design challenges, such as reducing the display form factor without sacrificing (or increasing) the headbox size, and reducing distortion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 0150453 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0103160 [Patent Document 3] U.S. Patent Application Publication No. 2021 / 0356760 [Patent Document 4] U.S. Patent No. 10,768,442 [Patent Document 5] U.S. Patent No. 11,196,976 [Patent Document 6] U.S. Patent Application Publication No. 2022 / 0057647 Summary of the Invention [Problem to be solved by the invention]

[0007] In describing this disclosure, references to "an embodiment," "one embodiment," or similar phrases mean that the described feature, function, structure, or characteristic is an example. Appearances of such phrases in this disclosure do not necessarily all refer to the same embodiment. Conversely, embodiments referenced in this disclosure are not necessarily mutually exclusive.

[0008] All illustrations and drawings illustrate selected versions of the technology introduced in this disclosure and are not intended to limit the scope of the technology introduced in this disclosure. All references to a "user" refer to an individual who utilizes the technology introduced in this disclosure.

[0009] Coaxial light field displays provide depth perception to users at a monocular level by manipulating the optical wavefront using field-evolving cavities (FECs). FECs are described in detail in U.S. Patent Nos. 5,629,997; 5,729,997; 5,729,997; and 5,729,997. All of these patents are incorporated by reference in their entirety into this disclosure. Coaxial light field displays are also described in detail in at least U.S. Patent No. 5,729,997. This mechanism enables optical depth modulation, effectively eliminating accommodation-vergence mismatch, providing comfortable viewing and significantly reducing eye stress and fatigue. The technology introduced in this disclosure is an FEC with an active material layer, a shielding layer, multiple seed display panels, and multiple one-dimensional (1D-1D) curved optical structures. These types of displays can provide tunable optical depth modulation and full or partial (fractional) light field signaling capabilities. This reduces the overall system footprint, improves signal-to-noise performance, and provides the ability to multiplex detailed information across the entire field of view. The term "one-dimensional" (1D) in this context refers to the property of an optical component having optical focusing power in one dimension. As used in this disclosure, the term "1D-1D curved" refers to the optical property of an optical component having multiple distinct layers of curvature that are orthogonal to each other. For example, a reflector may have a Fresnel lens that provides an effective curvature about a first axis on top of a reflective structure that is physically curved along a second axis that is orthogonal to the first axis.

[0010] This approach can be contrasted with four major existing light field display methods: super multiview, computational, holographic, and multifocal. Each of these methods has its own associated advantages and disadvantages (see Patent Documents 1, 2, and 4). Super multiview light field displays can be realized in a compact form factor, but the displayable zone is reduced and limited, resulting in limited resolution. Computational approaches offer mechanisms for increasing resolution, but suffer from haze and temporal flickering artifacts. Common issues when using holographic methods include significant color non-uniformity and fringing or mirror reflection artifacts. In contrast, multifocal light field display methods can provide clear images, but typically have large and bulky form factors. Aside from these issues, current light field display methods all typically suffer from a wide bandwidth requirement, a reliance on expensive and / or sophisticated components that are not easy to manufacture at scale (such as tunable lenses), poor color uniformity, narrow viewing zones or low visibility, small apertures, low brightness, haze and diffraction artifacts, limited depth range, lack of compatibility with existing display drivers, low bulk, and the need to wear special glasses. As a result, these limitations and challenges have limited the adoption and production of light field displays in commercial and / or enterprise settings and applications. Based on these limitations, new technologies are desired that are more compact, can be manufactured at lower cost, and can provide a wider viewing zone with greater comfort. [Means for solving the problem]

[0011] This disclosure introduces different light field display embodiments and systems that use tunable compression FEC and light field signaling. Four main architectures are introduced here: 1) FEC cavity design for tuning optical depth in light field displays using stacks of switchable reflectors to control depth in increments; 2) a compression design that increases the optical path of the object to the curved reflector while keeping the device thickness small; 3) Multi-display designs that support multiple layers of depth by using multiple individual displays on different sides of the optical cavity; and 4) Alternative FEC embodiments that use 1D-1D curved optical surfaces and diffractive optical elements (DOEs) to mimic 2D imaging effects for optical wavefront control by using components with reduced manufacturing tolerances and complexity.

[0012] This disclosure then describes content depth layer mapping techniques for both imaging and display applications of such cavities. Next, embodiments of each of the four architectures described above are disclosed. This disclosure also describes modulation of acoustic or mechanical waves into 1D-1D architectures, where the configuration or macroforming of these mechanical waves into reflective surfaces affects the control of optical wavefronts in different FEC architectures. This disclosure also describes hybrid 1D-1D approaches in which the lensing or wavefront effect is generated by geometric shaping in one dimension, and this is followed by a diffractive or refractive approach in the other perpendicular dimension to provide the equivalent of a two-dimensionally curved ("2D curved") reflector or surface (a "2D curved" reflector is a reflector with curvature about two orthogonal axes). Furthermore, this discloses several applications of these embodiments to in-vehicle visualization devices, watches, and various other scenarios.

[0013] Terminology In this disclosure, the term "arbitrarily designed" means any shape, size, material, feature, type, kind, orientation, position, quantity, structure, composition, component, and arrangement of components, having a single or array, that will enable the described technology or particular component thereof to achieve the purpose and intent of the technology or particular component thereof.

[0014] In this disclosure, a "light field" at a plane refers to a vector field that describes the amount of light flowing in all or a few selected directions through all points in that plane. A "light field" represents the angles and intensities of light rays passing through or exiting that plane. In this disclosure, a light field refers to a subsampled version of the full light field, such that the full light field vector field is represented by a limited number of samples at different focal planes and / or angles.

[0015] In this disclosure, "depth modulation" refers to the changing, programming, or variation of the monocular optical depth of a display or image. "Monocular optical depth" refers to optical depth that is directly related to the perceived distance between the user and the light source. An ideal light source emits light rays evenly in all directions, and the collection of light rays can be understood as lying on a sphere of increasing radius, called a wavefront. If the emitted image (e.g., an illuminated object or display) moves away from the observer, the emitted light travels a longer distance, and the user observes a spherical wavefront with a larger radius and correspondingly smaller curvature, i.e., the wavefront appears flatter. This reduction in curvature is perceived as greater depth by the eye or camera. Monocular optical depth does not require two eyes or perceived stereopsis. Wavefront generation refers to the change in wavefront curvature due to the propagation of light.

[0016] In this disclosure, the term "optically coupled" means that an element is adapted to impart, transmit, provide, or direct light to another element directly or indirectly.

[0017] In this disclosure, the term "chief ray" refers to the central axis of the light cone coming from a particular pixel or point in space.

[0018] In this disclosure, the terms "field evolving cavity" and "FEC" refer to a non-resonant (e.g., unstable) cavity that propagates light back and forth within its reflectors, generating a wavefront shape associated with the light in physical space. An example of an FEC can include two or more half- or semi-transparent mirrors facing each other. As described in this disclosure, an FEC may be parallel to the display plane (in the case of a display system) or the entrance pupil plane (in the case of an imaging system). An FEC may also be used to change the apparent depth of a display or section of a display. In an FEC, light travels back and forth or circulates between the facets of the cavity. Each of these propagations is called a "path." For example, consider an FEC with two reflectors, one at the light source side and the other at the exit side. The first instance, where light propagates from the entrance reflector to the exit reflector, is called the forward path. When light, or a portion of light, is reflected from the exit facet back to the entrance facet, the light propagates backward toward the light source, and the propagation is called the backward path. Within the cavity, a round trip occurs when light completes one cycle and returns to the entrance facet. FECs come in a variety of architectures, but the principle is the same. An FEC is an optical architecture that creates multiple paths for light to travel, either by forcing the light to make more round trips, or by forcing light from different sections of the same display to travel different distances before exiting the cavity. If light exits the cavity perpendicular to the angle at which it entered the cavity, the FEC is called an off-axis FEC or "normal-emitting FEC."

[0019] In this disclosure, the term "round trip" refers to the number of times light circulates or makes a round trip between the entrance and exit facets or layers of a cavity.

[0020] In this disclosure, an "aperture of a display system" is a surface from which light exits the display system toward the exit pupil of the display system. The aperture is a physical surface, while the exit pupil is a virtual image surface that may or may not be superimposed on the aperture. After the exit pupil, the light enters the outside world.

[0021] In this disclosure, an "aperture of an imaging system" is the area or surface where light enters the imaging system and propagates toward the sensor after the entrance pupil of the imaging system, which is the imaginary surface or plane where light first enters the imaging system.

[0022] In this disclosure, the term "display" refers to any device that emits light that forms (at least in part) the image displayed to the user. Thus, the term "display" refers to an "emissive display," which may be based on any technology, including, but not limited to, liquid crystal displays (LCDs), thin-film transistors (TFTs), light-emitting diodes (LEDs), organic light-emitting diode arrays (OLEDs), active-matrix organic light-emitting diodes (AMOLEDs), plastic organic light-emitting diodes (POLEDs), micro-organic light-emitting diodes (MOLEDs), or projection-on-angle or angle-projection array-dependent diffusing screens, or other display technologies, and / or mirrors, and / or semi-mirrors, and / or dimming mirrors, or liquid crystal sheets arranged and assembled to emit light beams with diverging apexes at different depths or at a single depth, or core-plane or waveguide-based displays. Unless otherwise specified, the display may be an autostereoscopic display that provides stereoscopic depth with or without glasses. It may be curved, flat, bent, or an array of small displays tiled in any configuration. The display may be a near-eye display for a headset, a near-head display, or a distant display. The application of the display does not affect the principles of the technology introduced in this disclosure.

[0023] In this disclosure, "angular profiling" refers to manipulating light beams to travel in a specific direction. This can be achieved using holographic optical elements (HOEs), diffractive optical elements (DOEs), lenses, concave or convex mirrors, lens arrays, microlens arrays, aperture ray arrays, optical phase or amplitude masks, digital mirror devices (DMDs), spatial phase modulators (SLMs), metasurfaces, diffraction gratings, interference films, privacy films, or other methods. Intensity profiling can be achieved using absorbing or reflective polarizers, absorbing coatings, gradient coatings, or other methods. Color or wavelength profiling can be achieved using color filters, absorbing notch filters, interference films, or other methods. Polarization profiling may be performed using metasurfaces with metallic or dielectric materials, micro- or nanostructures, wire grids, absorbing polarizers, quarter-wave plates, half-wave plates, 1 / x wave plates, isotropic or spatially profiled wave plates, or other nonlinear crystals.

[0024] In this disclosure, the terms "active design," "active component," or generally "active" refer to designs or components with variable optical properties that can be altered by optical or electrical signals. Electro-optical (EO) materials include liquid crystals (LCs) with transparent electrodes on either side that change the refractive index by applying an electric field; liquid crystals as variable retarders (LCVRs); and piezoelectric materials / layers that exhibit the Pockels effect (also known as electro-optical refractive index change), such as lithium niobate (LiNbO), lithium tantalate (LiTaO), potassium titanyl phosphate (KTP), strontium barium niobate (SBN), and beta-barium borate (BBO). EO materials can be designed in any way. Passive designs or components refer to designs that have no active components other than the display.

[0025] In this disclosure, the "pass angle" of a polarizer refers to the angle at which incident light perpendicular to the surface of the polarizer can pass through the polarizer with maximum intensity. Two items are "cross-polarized" when their polarization states or directions are orthogonal to each other. For example, if two linear polarizers are cross-polarized, their pass angles differ by 90 degrees.

[0026] In this disclosure, a "reflective polarizer" refers to a polarizer that transmits light with polarization aligned with the polarizer's pass axis and reflects light polarized cross-polarized to its pass axis. An example of such a polarizer is a "wire grid polarizer" (a reflective polarizer with parallel nanowires). An "absorptive polarizer" is a polarizer that transmits light with polarization aligned with the polarizer's pass angle and absorbs cross-polarized light. A "beamsplitter" is a semi-reflective layer that reflects a specific desired percentage of light intensity, which can be polarization-dependent, and transmits the remaining light. A simple example of a beamsplitter is a glass slab with a semi-transparent silver or dielectric coating that transmits 50% of the light and reflects the other 50%.

[0027] In this disclosure, an "imaging sensor" can use any image sensing technology to acquire light or a particular parameter of light exposed thereon. Examples of such imaging sensing technologies include complementary symmetric metal-oxide semiconductor (CMOS), single-photon avalanche diode (SPAD) arrays, charge-coupled devices (CCDs), intensified charge-coupled devices (ICCDs), ultrafast streak sensors, time-of-flight sensors (ToF), Schottky diodes, or other short- or long-wavelength optical or electromagnetic sensing mechanisms.

[0028] As used in this disclosure, "imaging system" means any device that acquires an image, which is a matrix of information about light intensity and / or its phase, temporal, spectral, polarization, entanglement, or other properties used in any application or framework. Imaging systems include cell phone cameras, industrial cameras, photographic or video cameras, microscopes, telescopes, spectrometers, time-of-flight cameras, ultrafast cameras, thermal cameras, or other types of imaging systems.

[0029] In this disclosure, the term "macroforming" refers to forming the surface geometry / curvature of an optical element where the optical features have a periodicity of at least 1 millimeter (as opposed to "microforming," where the optical features have a periodicity of less than 1 millimeter and sub-wavelength structures are created).

[0030] The technology presented in this disclosure builds on certain aspects of the aforementioned display systems (see Patent Documents 1-4) and generates high-quality virtual images that can be 2D, stereoscopic 3D, and / or multifocal images. Here, the display system has an intended (designed) viewpoint for a human observer at least 10 cm away from the display (as opposed to a conventional head-mounted display (HMD)). The technology presented in this disclosure extends previous techniques that generate a single, continuous light field that enables simultaneous detection of monocular depth by each eye of the human observer. The monocular depth can be greater than the actual distance from the human observer to the display, and provides an apparent size of the display (as perceived by the human observer) that is greater than the actual size of the display when the human observer is positioned at the intended viewpoint. Using the technology presented in this disclosure, the accessible monocular depth is also dynamically tunable with respect to depth location and profile, and, in contrast to current autostereoscopic displays, the number of depth layers created across the user's field of view is not fixed to the physical location on the surface of the display panel. It should be noted that any of the techniques presented below can be adapted or modified to create an imaging system (e.g., a camera system) capable of producing multi-layered, multi-zoomable images. This can be achieved by retaining the same physical / optical configuration as described below and replacing the active display elements (e.g., LEDs or similarly-purposed elements) with one or more photosensors (e.g., CCDs or similarly-purposed elements).

[0031] In some embodiments, a display system according to the technology introduced in this disclosure is placed approximately 20 cm from the observer's eyes and is designed to provide an apparent display size (i.e., the size perceived by a human observer) of approximately 100 inches. In this case, 10% of the peripheral virtual screen at the diagonal edge of the field of view has a different modulated image depth than the central region, or multiple depth levels exist in different parts of the field of view. In this context, "horizontal" means parallel to an imaginary line passing through the geometric centers of a human observer's eyes when the human observer views the display in the normal (intended) manner.

[0032] The techniques introduced in this disclosure enable the generation of a coaxial light field with monocular-binocular hybridization, adding depth modulation tunability and light field signaling capabilities, and using compressed FEC implementations with 1D-1D and DOE components to reduce manufacturing complexity and system size. As used in this disclosure, the term "coaxial light field" (also referred to as a "curved light field") refers to a light field in which, for any two pixels (referred to as a "first pixel" and a "second pixel") of a display located at a fixed radius from the observer, the chief ray of the light cone emanating from the first pixel in a direction perpendicular to the plane of the display intersects with the chief ray of the light cone emanating from the second pixel in a direction perpendicular to the plane of the display at the first pixel. A coaxial light field generates an image that can be focused by the eye at all points, including pixels far from the optical axis (center of curvature) of the system. Here, this image is curved rather than flat, and the image is viewable within a specific viewing space (headbox) in front of the light field. [Brief explanation of the drawings]

[0033] [Figure 1] 1 illustrates a set of elements that can be used to construct various embodiments of the field-generated cavity (FEC) described in this disclosure. [Figure 2A] 2A-2C illustrate various arrangements of the elements of FIG. 1 to produce different architectures of the FEC embodiments described in this disclosure. [Figure 2B] 2A-2C illustrate various arrangements of the elements of FIG. 1 to produce different architectures of the FEC embodiments described in this disclosure. [Figure 2C] 2A-2C illustrate various arrangements of the elements of FIG. 1 to produce different architectures of the FEC embodiments described in this disclosure. [Figure 3A] FIG. 1 shows a perspective view of an exemplary embodiment including multiple stacks that are dimmable for depth modulation. [Figure 3B] 1 illustrates a perspective view of an exemplary embodiment including a compressed cavity. [Figure 3C] 1 shows a perspective view of an exemplary embodiment including multiple seed display panels. [Figure 3D] 1 illustrates a perspective view of an exemplary embodiment including a 1D-1D geometry. [Figure 3E] FIG. 3B is another view of the embodiment of FIG. 3A, in which the multi-layer component is shown in "exploded" form. [Figure 3F] FIG. 3C is another view of the embodiment of FIG. 3B, in which the multi-layer component is shown in "exploded" form. [Figure 3G] FIG. 3D is another view of the embodiment of FIG. 3C, in which the multi-layer component is shown in "exploded" form. [Figure 3H] FIG. 3E is another view of the embodiment of FIG. 3D in which the multi-layer components are displayed in an "exploded" format. [Figure 4A] 1 shows a block diagram representation of a process for obtaining 2D or 3D content and generating a three-dimensional display. [Figure 4B] 1 shows a block diagram representation of the process of capturing and recording a 3D image of a scene in a computer. [Figure 5A] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5B]3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5C] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5D] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5E] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5F] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5G] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5H] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5I] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5J] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 5K] 3B shows a side view of an exemplary embodiment using the dimming stack of FIG. 3A with multiple configurations and various dimming elements. [Figure 6A] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6B] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6C]3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6D] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6E] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6F] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6G] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6H] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6I] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6J] 3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 6K]3C shows a side view of an exemplary embodiment for generating a compressed display or a light field display from FIG. 3B to increase headbox space and obtain a mosaic virtual image. [Figure 7A] 3D shows a side view of an exemplary embodiment using multiple seed panels from FIG. 3C with single and higher order FEC. [Figure 7B] 3D shows a side view of an exemplary embodiment using multiple seed panels from FIG. 3C with single and higher order FEC. [Figure 7C] 3D shows a side view of an exemplary embodiment using multiple seed panels from FIG. 3C with single and higher order FEC. [Figure 7D] 3D shows a side view of an exemplary embodiment using multiple seed panels from FIG. 3C with single and higher order FEC. [Figure 7E] 3D shows a side view of an exemplary embodiment using multiple seed panels from FIG. 3C with single and higher order FEC. [Figure 7F] 3D shows a side view of an exemplary embodiment using multiple seed panels from FIG. 3C with single and higher order FEC. [Figure 8A] 3D shows a side view of an exemplary embodiment that uses a different 1D-1D architecture, generalizes from FIG. 3D, and includes both static and mechanically modulated layers. [Figure 8B] 3D shows a side view of an exemplary embodiment that uses a different 1D-1D architecture, generalizes from FIG. 3D, and includes both static and mechanically modulated layers. [Figure 8C] 3D shows a side view of an exemplary embodiment that uses a different 1D-1D architecture, generalizes from FIG. 3D, and includes both static and mechanically modulated layers. [Figure 8D] 3D shows a side view of an exemplary embodiment that uses a different 1D-1D architecture, generalizes from FIG. 3D, and includes both static and mechanically modulated layers. [Figure 8E]3D shows a side view of an exemplary embodiment that uses a different 1D-1D architecture, generalizes from FIG. 3D, and includes both static and mechanically modulated layers. [Figure 8F] 3D shows a side view of an exemplary embodiment that uses a different 1D-1D architecture, generalizes from FIG. 3D, and includes both static and mechanically modulated layers. [Figure 8G] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8H] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8I] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8J] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8K] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8L] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8M] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8N] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8O]3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 8P] 3D shows a side view of an exemplary embodiment using a different 1D-1D architecture, generalized from FIG. 3D, and including both static and mechanically modulated layers. [Figure 9A] 1 shows two simulated ray diagrams with increased headbox space and increased eye distance for a display system with multiple reflections of light within the cavity compared to a single reflection display system. [Figure 9B] 1 shows two simulated ray diagrams with increased headbox space and increased eye distance for a display system with multiple reflections of light within the cavity compared to a single reflection display system. [Figure 10A] 1 shows a simulated ray diagram of a 1D-1D cavity. [Figure 10B] 1 shows a simulated ray diagram of a 1D-1D cavity. [Figure 11A] 10A and 10B illustrate the fabrication of several subsampled diffractive elements. [Figure 11B] 10A and 10B illustrate the fabrication of several subsampled diffractive elements. [Figure 11C] 10A and 10B illustrate the fabrication of several subsampled diffractive elements. [Figure 12A] 10A-10C illustrate various headset displays that serve as examples of additional embodiments of the display system and its integration with stereoscopic display methods. [Figure 12B] 10A-10C illustrate various headset displays that serve as examples of additional embodiments of the display system and its integration with stereoscopic display methods. [Figure 12C] 10A-10C illustrate various headset displays that serve as examples of additional embodiments of the display system and its integration with stereoscopic display methods. [Figure 12D]10A-10C illustrate various headset displays that serve as examples of additional embodiments of the display system and its integration with stereoscopic display methods. [Figure 13A] An additional portable embodiment is shown that can be implemented in automobiles or smart devices for various applications in different configurations. [Figure 13B] An additional portable embodiment is shown that can be implemented in automobiles or smart devices for various applications in different configurations. [Figure 13C] An additional portable embodiment is shown that can be implemented in automobiles or smart devices for various applications in different configurations. [Figure 14] 1 is a flowchart illustrating a process according to a technique as introduced in this disclosure. [Figure 15A] 1A-1C illustrate two different perspective views of an exemplary headset incorporating the display technology introduced in this disclosure. [Figure 15B] 1A-1C illustrate two different perspective views of an exemplary headset incorporating the display technology introduced in this disclosure. [Figure 15C] 1 shows a headset displaying multiple virtual objects at different virtual depths. [Figure 16A] 1 illustrates an embodiment of a display system integrated into a center console display. [Figure 16B] 1 illustrates an embodiment of a display system integrated into a center console display. [Figure 16C] 1 illustrates an embodiment of a display system integrated into a center console display. [Figure 17A] 1 illustrates an embodiment of a display system that is integrated into a center console display and features a virtual image closer to the viewer than the display device. [Figure 17B] 1 illustrates an embodiment of a display system that is integrated into a center console display and features a virtual image closer to the viewer than the display device. [Figure 17C] 1 illustrates an embodiment of a display system that is integrated into a center console display and features a virtual image closer to the viewer than the display device. [Figure 17D] 1 shows a side view of an embodiment of a display system featuring retroreflective and retrorefractive optical elements. [Figure 17E] 1 shows a side view of an embodiment of a display system featuring retroreflective and retrorefractive optical elements. [Figure 18A] 1 illustrates an embodiment of a display system with an expanded view aperture. [Figure 18B] 1 illustrates an embodiment of a display system with an expanded view aperture. [Figure 18C] 1 illustrates an embodiment of a display system with an expanded view aperture. [Figure 18D] 1 illustrates an embodiment of a display system with an expanded view aperture. [Figure 18E] 1 illustrates an embodiment of a display system with an expanded view aperture. [Figure 19A] 1 illustrates an embodiment of a display system that functions as or is part of an instrument cluster behind the steering wheel of a vehicle. [Figure 19B] 1 illustrates an embodiment of a display system that functions as or is part of an instrument cluster behind the steering wheel of a vehicle. [Figure 19C] 1 illustrates an embodiment of a display system that functions as or is part of an instrument cluster behind the steering wheel of a vehicle. [Figure 19D] 1 illustrates an embodiment of a display system that functions as or is part of an instrument cluster behind the steering wheel of a vehicle. [Figure 19E]1 illustrates an embodiment of a display system that functions as or is part of an instrument cluster behind the steering wheel of a vehicle. [Figure 19F] 1 illustrates an embodiment of a display system that functions as or is part of an instrument cluster behind the steering wheel of a vehicle. [Figure 20A] 1A-1D illustrate various embodiments of a display system using 1D-1D or curved elements. [Figure 20B] 1A-1D illustrate various embodiments of a display system using 1D-1D or curved elements. [Figure 20C] 1A-1D illustrate various embodiments of a display system using 1D-1D or curved elements. [Figure 21A] 1 shows an embodiment of a display system integrated into the steering column of a vehicle and having an opening in the steering wheel. [Figure 21B] 1 shows an embodiment of a display system integrated into the steering column of a vehicle and having an opening in the steering wheel. [Figure 21C] 1 shows an embodiment of a display system integrated into the steering column of a vehicle and having an opening in the steering wheel. [Figure 22A] 1 is a schematic overhead view of a vehicle in which a display system generates virtual images using reflections from the interior surfaces of the vehicle's windows. [Figure 22B] 1 shows an interior view of a vehicle in which a display system creates a virtual image using reflections from the interior surfaces of the vehicle's windows. [Figure 22C] 1 shows an interior view of a vehicle in which a display system creates a virtual image using reflections from the interior surfaces of the vehicle's windows. [Figure 22D] 1 shows an interior view of a vehicle in which a display system creates a virtual image using reflections from the interior surfaces of the vehicle's windows. [Figure 22E]1 shows an interior view of a vehicle in which a display system creates a virtual image using reflections from the interior surfaces of the vehicle's windows. [Figure 22F] 1 shows a schematic diagram of an embodiment of a display system that uses reflections from the interior surfaces of vehicle windows to generate virtual images. [Figure 22G] 1 shows a schematic diagram of an embodiment of a display system that uses reflections from the interior surfaces of vehicle windows to generate virtual images. [Figure 22H] 1 shows a schematic diagram of an embodiment of a display system that uses reflections from the interior surfaces of vehicle windows to generate virtual images. [Figure 23] 1 shows an exterior view of a vehicle that collects light from the vehicle's reverse view and uses that light to form a virtual image. [Figure 24A] 1 shows various views of a vehicle that uses a camera to collect light that is not visible to the driver and displays the resulting information as a virtual image. [Figure 24B] 1 shows various views of a vehicle that uses a camera to collect light that is not visible to the driver and displays the resulting information as a virtual image. [Figure 24C] 1 shows various views of a vehicle that uses a camera to collect light that is not visible to the driver and displays the resulting information as a virtual image. [Figure 25] 1 shows an exterior view of a vehicle that uses a display system to present annotated information to a driver about characteristics of the surrounding environment. [Figure 26A] 1 shows an exterior view of a vehicle that uses a display system to present information to a driver about the characteristics of the surrounding environment in poor visibility conditions. [Figure 26B] 1 illustrates an embodiment of a display system that uses a windshield as the reflective element of the display system. [Figure 26C] 1 illustrates an embodiment of a display system that uses a windshield as the reflective element of the display system. [Figure 27]10 shows a side video of an embodiment that computationally pre-compensates a virtual image to reduce or eliminate unwanted ghost reflections from the windshield. [Figure 28A] 1 illustrates an embodiment of a display system for simultaneous use by multiple viewers as an entertainment system. [Figure 28B] 1 illustrates an embodiment of a display system for simultaneous use by multiple viewers as an entertainment system. [Figure 28C] 1 illustrates an embodiment of a display system for simultaneous use by multiple viewers as an entertainment system. [Figure 29A] 1 shows an embodiment in which the display system is integrated into the exterior lights of the vehicle for viewing by an observer outside the vehicle. [Figure 29B] 1 shows an embodiment in which the display system is integrated into the exterior lights of the vehicle for viewing by an observer outside the vehicle. [Figure 29C] 1 shows an embodiment in which the display system is integrated into the exterior lights of the vehicle for viewing by an observer outside the vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0034] FIG. 1 illustrates some basic "building block" components of the embodiments described in this disclosure. These components can be designed arbitrarily. Element 1 is a schematic diagram of an emissive display. Element 2 represents a sensor, which can be an optical sensor, a camera sensor, a motion sensor, or generally an imaging sensor. Element 3 is a schematic diagram of a mirror, which can be a first-surface mirror, a second-surface mirror, or generally any reflective surface. Element 4 is a free-form optical element, which can represent any free-form optical element, convex or concave, or other convex, concave, or convex or concave surface represented by any function, or neither. Element 5 is a representation of a curved display. Element 6 represents an electro-optic material, such as a liquid crystal (LC). Element 7 represents an electro-optic (EO) polarization rotator, which can rotate linearly polarized light to a desired angle by changing the signal voltage. Element 8 is an absorptive polarizer, which passes one polarization of light and absorbs the perpendicular polarization of light.

[0035] Element 9 is a half-wave plate (HWP) that produces a 180° relative phase shift between the vertically polarized components propagating through it. For linearly polarized light, this has the effect of rotating the polarization direction by an amount equal to twice the angle between the initial polarization direction and the axis of the wave plate. Element 10 is a quarter-wave plate (QWP) that produces a 90° relative phase shift. This converts linearly polarized light to circularly polarized light, and this converts circularly polarized light to linearly polarized light.

[0036] Element 11 is an angular profiling layer, which is a layer optionally designed to produce a specified angular distribution of light rays.

[0037] Element 12 is a liquid crystal (LC) plate that is switched "ON." In this state, the LC plate rotates the polarization of light passing through it. Element 13 is an LC plate that is switched "OFF." In this OFF state, the polarization state of light is unchanged as it passes through the LC plate.

[0038] Element 14 is a diffractive optical element (DOE), which has microstructures that create a diffractive effect. The DOE can be made of any material.

[0039] Elements 15 are mechanical actuators that can be actuated by electrical or other types of signals to physically move the elements to which they are connected.

[0040] Element 16 is a full switchable mirror in the "ON" configuration, and element 17 is a full switchable mirror in the "OFF" configuration. When the switchable mirror is ON, it is reflective. When it is OFF, it is transparent. The mirror can also be in a semi-transparent state.

[0041] Element 18 is a retroreflector, which is a mirror that reflects light rays in exactly the same direction they are incident on. Retroreflectors can be fabricated from microstructures such as microspheres, microcorner cubes, metasurface stacks, or can be nonlinear elements.

[0042] Element 19 is a beam splitter that partially reflects and partially transmits light, and the ratio of reflected light to transmitted light can be designed as desired.

[0043] Element 20 is a polarization-dependent beam splitter (PBS), which reflects light of one polarization and transmits the orthogonal polarization. PBSs can be optionally designed and fabricated using reflective polymer stacks, nanowire grids, or thin-film technology.

[0044] Element 21 is a lens group, which may include one or more lenses of any focal length, concavity, and orientation.

[0045] Element 22 is a one-dimensional (1D) curved optical component, which is curved or arbitrarily designed in one direction but has a uniform structure in the perpendicular direction.

[0046] Element 23 represents a ray of x-polarized light, whose polarization direction is in the plane of the page of the side view sketch. Element 24 represents a ray of y-polarized light, orthogonal to element 23, whose polarization direction is perpendicular to the plane of the side view embodiment sketch. Element 25 represents a ray of circularly polarized light. Such light contains both x-polarized and y-polarized light, with the two components 90 degrees out of phase, and the polarization direction moves in a circle as the light propagates. This circular polarization can be clockwise or right-handed circular polarization (RCP) or counterclockwise or left-handed circular polarization (LCP).

[0047] Elements 26 represent electrical signals used in the electrical system associated with the display system to modulate optical elements or provide feedback to a computer.

[0048] Element 27 is an antireflection (AR) layer designed to eliminate reflections of light incident on its surface. Element 28 is an absorptive layer that absorbs all incident light. Element 29 is a microcurtain layer that redirects light in a specific direction or blocks light from traveling in a specified direction. Microcurtains can be made by embedding a thin, periodic absorbing layer into a polymer or glass substrate, or by melting a thin, black-coated glass and cutting a cross-section slab.

[0049] The basic elements of Figure 1 can be combined to produce the functional elements, subassemblies, or subsystems shown in Figures 2A-2C. In Figure 2A, element 30 (QBQ) comprises a QWP, a beam splitter, and another QWP. Element 31 (QM) comprises a QWP stacked on a mirror. It reflects all light and converts x-polarized light to y-polarized light and y-polarized light to x-polarized light. It leaves circularly polarized light unchanged.

[0050] Element 32 is an electro-optic shutter containing an LC layer and an absorptive polarizer. When the LC is ON, it rotates the polarized incident light so that it is aligned perpendicular to the absorptive polarizer and the incident light is absorbed by the absorptive polarizer. When the LC layer is OFF, it does not change the polarization, leaving it parallel to the absorptive polarizer, so the light is transmitted. Element 33 is an electro-optic reflector containing an LC layer and a PBS. When the LC layer is ON, the polarization rotates to be aligned with the transmission direction of the PBS. When the LC layer is OFF, the light passing through the LC layer is aligned to be reflected by the PBS.

[0051] Element 34 is a full switchable black mirror (FSBM). In the ON state, the full switchable mirror is ON and reflects all polarizations. In the OFF state, the switchable layer and the absorbing layer together eliminate x-polarized light, transmit y-polarized light, and transmit only the y component of circularly polarized light. Element 35 is a full switchable black mirror (FSBMQ) with a quarter-wave plate, including an FSBM with an added QWP layer. In the ON state, it reflects all light and exchanges x-polarized light with y-polarized light. It reflects circularly polarized light unchanged. In the OFF state, it eliminates circular polarization, transmits y-polarized light, and converts x-polarized light to y-polarized light, transmitting the result.

[0052] Two switchable reflective stacks are shown in Figure 2B. Element 36 is a switchable black mirror with a quarter-wave plate (SBMQ) containing a QWP, followed by two alternating LC and PBS layers and an absorptive polarizer. The difference between a fully switchable mirror (FSBMQ) and a switchable mirror (SBMQ) is the dependence of the reflectivity on polarization. In the former, the total reflectivity of the material changes independently of the polarization of the incident light, while the purpose of the latter is to allow the reflectivity to depend on polarization.

[0053] In element 36, when both LC layers are OFF (transmission mode), all incident polarized light transmits the x-polarized component. When the first LC layer is ON and the second LC layer is OFF (reflection mode), circularly polarized light is reflected unchanged, y-polarized light is reflected as x-polarized light, and x-polarized light is reflected as y-polarized light. When the first LC layer is OFF and the second LC layer is ON (absorption mode), all incident light hits the absorbing layer and is extinguished, and no light is transmitted through the absorbing layer.

[0054] Element 37 is an electro-optical reflector stack (EORS) that includes a stack of N alternating PBS and LC layers. All but one LC layer is in the OFF state, and the LC layer in the ON state reflects incident x-polarized light. All other layers transmit light. By varying which LC layer is in the ON state, the EORS modulates the optical depth, or optical path, or length that light must travel through the stack before being reflected by the cross-polarized PBS layer next to the ON LC layer.

[0055] FIG. 2C shows various combinations of elements forming field-generating cavities (FECs) or layer stacks that can be used as subsystems in the architectures described throughout this disclosure. Elements 38 and 39 are the OFF and ON states, respectively, of a display and a QBQ followed by an electro-optic reflector. Here, in the OFF state, light exits directly through the aperture. In the ON state, light is forced to make one round trip through the cavity, and the displayed image appears to be deeper than its actual location in the display. Element 40 is a display followed by a QBQ and a PBS attached to a mechanical actuator. This actuator shifts a series of layers to lengthen or shorten the optical path length of the light. Element 41 is a mechanical actuator fixed to the display. This actuator can shift or macro-form the display relative to an angular profiling layer, forcing the light to change direction or collimate it more or less. In some embodiments, the angular profiling layer could be a lenslet array such that mechanical movement of the display changes the object distance and therefore affects the collimation. In some embodiments, the display could be macroformed by a mechanical actuator to create a mechanical wave or bend in the display to have a desired effect on the directionality or collimation of the light coming from the angular lenslet array.

[0056] In some embodiments, movement of the actuator along a translational axis may mechanically shift the display to affect the directionality of light emitted from the aperture. The mechanical actuation mechanism may be arbitrarily designed. In some embodiments, the mechanical actuator may be an array of ultrasonic transducers. In some embodiments, the mechanical translation may be performed by a high revolutions per minute brushless motor. In some embodiments, the mechanical motion may be transmitted via a piezo or stepper motor based mechanism.

[0057] Element 42 is a cavity containing a display divided into segments. Light from the lower segment is reflected by a mirror, and light from the upper segment is reflected by a subsequent beam splitter. An absorbing layer absorbs unwanted stray light. This is an example of an off-axis FEC. This FEC can be arbitrarily designed to exhibit any desired number of layers (see patents 1-4).

[0058] Element 43 is a display layer immediately followed by an angular profiling layer, which may be a lenticular lens array that provides a stereoscopic view to the viewer, or a lenslet array or other angular profiling layer that provides autostereoscopic 3D or provides different images at different angles.

[0059] Element 44 is a tilted display layer followed by a cavity with an internal polarization clock, whose ends are made of PBS layers. Between the PBS layers is a birefringent layer 45 so that different propagation angles result in different polarization delays. The aperture shutter layer allows only one of the round trips to exit the cavity, and the transmitted light is tuned to the desired polarization so that it travels the desired optical path or optical depth. This represents a coaxial FEC with a segmented, gated aperture, equipped with a polarization clock and the desired gating mechanism (see Patent Documents 2 and 3).

[0060] Element 46 is a display followed by a microcurtain layer and a QWP, which function as pre-cavity optics. This allows for a desired light profile for the display. This pre-cavity optic can tune the polarization, angular distribution, or other properties of the light entering the cavity. Element 47 is a stack of layers consisting of a display layer, a QWP, a microcurtain layer, and an anti-reflection (AR) layer. This subsystem is used in many other disclosed systems and is classified as a display. The microcurtain can be designed arbitrarily, allowing for control of the light directionality or visibility of the display. The AR layer allows for reduction of ambient or internal reflections in systems using this subcomponent. Element 48 is a subassembly that includes a transparent substrate with an AR coating and an absorbing polarizer on one side facing the user and the outside world, and another AR coating or film and a QWP on the side facing the display, which emits light. In this disclosure, 48 is referred to as the shield layer. Element 49 is a display subassembly with a microcurtain layer and an AR coating thereon. Device 50 shows a subassembly that includes two mirrors above and below, a display behind, and a tilted PBS with LC in the middle, so that an electronic signal to the LC can change the length the light needs to travel before exiting the cavity. In some embodiments, there may be a stack of such tilted PBS-on-LC splitters to allow the travel length of the light to be programmed or controlled in multiple steps. In some embodiments, the mirrors may be QMs to rotate the polarization of the light. In some embodiments, the reflectors can be curved and parabolic to increase depth.

[0061] It should be noted that certain features described below are constructed from the basic "building block" components shown in FIG. 1 and described above. These may be referred to as "composite" or "multi-layer" features. Such composite or multi-layer features may be referred to below and in subsequent figures by the name and corresponding reference number of the overall feature (e.g., semi-reflective optical element (110) in FIG. 3A), and such features may be referred to herein by their individual constituent ("building block") components or layers (e.g., semi-reflective optical element (110) may also be referred to as beamsplitter (19) with anti-reflective coating (27)). These alternative ways of referring to the same feature will be readily apparent and understood by those skilled in the art.

[0062] Figures 3A-3D show a series of exemplary embodiments representing four architectures for providing tunable depth modulation in coaxial near-head light field displays for first-order and higher-order FEC cavity designs. Figures 3E-3H are views of the embodiments of Figures 3A-3D, respectively, with the multilayer components shown in "exploded" form. These architectures provide multiple layers of depth and eye comfort by using longer focal lengths and increasing the object distance to the lens mechanism. They also provide compact architectures with a side aspect ratio of an elongated rectangle rather than a square. The FEC cavity has a series of pre-fabricated optical components that can have several alternative embodiments.

[0063] Figures 3A and 3E each show perspective views of an embodiment of a tunable coaxial near-head light field display. Here, an active dimming reflector is used to terminate one end of the cavity, and this active dimming reflector can be electronically addressed to tune the level of the resulting optical depth modulation. For example, in this embodiment, light is emitted from an emissive display or display array (1). The light from the display (1) then passes through a set of pre-cavity optical elements (29, 27) that tune the state of the light before passing through an FEC with fixed or dimming optical elements (37) that determine and tune the optical depth in desired increments. The light is then reflected by the dimming optical element 37 back to a semi-reflective optical element 110, created by internal passive optical elements (19, 27) within the cavity. This semi-reflective optical element 110 reflects the light toward a 2D curved (free-form) back reflector (111). The back reflector (111) can be made of a mirror (3) placed on a free-form optic (4). The light then reflects off the back reflector (111), passes through a semi-reflective optic, passes through a shielding layer (112) made of passive elements (8, 27, or 48), and travels towards the user's eyes (not shown).

[0064] The back reflector (111) can be arbitrarily designed. In some embodiments, the back reflector has a thin layer that affects the light properties. In some embodiments, this layer can be a thin glass layer with a thin QWP lamination (10). In some embodiments, the back reflector (111) can be a flat or curved DOE (13). In some embodiments, the back reflector (111) can be a flat or curved metasurface with nanostructures. In some embodiments, the back reflector (111) can be a tunable freeform curve.

[0065] In some embodiments, the layer stack of the photochromatic optical element (37) can include a reflective coating, an anti-reflective coating (27), a QWP (10), a HWP (9), or a partially absorbing layer. In some embodiments, the layer stack of the photochromatic optical element (37) is laminated or deposited on the back reflector (111). In some embodiments, the layer stack of the photochromatic optical element (37) works in conjunction with nanoimprinted structures on the back reflector (111) to change the direction of light. In some embodiments, the layer stack of the photochromatic optical element (37) can be adjusted in terms of polarization properties, reflectivity, or absorption properties using an electrical signal.

[0066] The shield layer (112) functionally mitigates non-uniformities (waviness) observed in the virtual image and reduces ambient light noise experienced by the user. Some ambient light reflects directly from the shield layer, and some ambient light enters the cavity and returns. The shield layer (112) can be a stack of layers laminated or deposited together so that light entering the cavity changes polarization and is absorbed by the stack of polymers. In some embodiments, the shield layer (112) is tilted or bent depending on the polarization of the signal light or image light to further reduce ambient light and internal cavity reflections. In some embodiments, the shield layer (112) is composed of an absorbing polarizer (8), a QWP (10), or an optional anti-reflection coating (27). In some embodiments, the shield layer (112) has an absorbing substrate (28) that further reduces ambient reflections because the ambient light passes through the shield layer twice. In some embodiments, the shield layer (112) comprises a liquid crystal layer (12, 13) or an optically tunable layer that can select the image depth required to exit the cavity using an electrical signal (26) applied to the shield layer (112). In some embodiments, there is a liquid crystal layer with an oscillating polarization on the shield layer to present both polarizations to the outside world.

[0067] As an extension of this mechanism, photochromic reflectors with higher-order FECs provide tunable multilevel depth modulation capabilities. For each j level of photochromic reflection (j = 1:M) that the LC stack layer can support, the total number of resulting optically modulated depth layers is calculated as a function of the FEC order i (i = 1:N), so that the number of optical depth layers is M.

[0068] Note that by using the configuration shown in Figure 3A, the depth of the display system can be less than half the focal length of the display system at maximum magnification. The "depth" of the display device in this context is the distance between the front-most point of the back reflector and the front-most point of the overall display system aperture.

[0069] The perspective views of the embodiment in Figures 3B and 3F show a compressed cavity with a thinner footprint than that shown in Figure 3A. Light exits the emissive display (1), passes through the pre-cavity optics (27, 10, 29), is reflected by a narrow beam splitter (117) made from intra-cavity elements (19, 27), is reflected by the 2D back reflector (116), and then passes through the beam splitter (117), the post-cavity optics, and the shielding layer (118). Stray light is absorbed by the absorbing layer (28) at the bottom of the cavity. This compressed embodiment allows the effective curvature of the curved back reflector 116 to be flattened, resulting in a flatter spatial distribution of the virtual image. This is achieved by thinning the entire body and allowing for a higher aperture, which effectively allows for a larger focal length at the maximum volumetric visibility zone compared to the "uncompressed" embodiment of Figure 3A. In this embodiment, the beam splitter (117) has at least one segment that partially reflects light back to the reflector (116), and the remaining portion interacts differently with the light from the display (1), so the distance from the center height of the beam splitter (117) to the center height of the back reflector (116) can be less than one-third the height of the back reflector (116). In some embodiments, the beam splitter (117) is or has a microcurtain layer (29) laminated onto it to provide additional flexibility in the angular profiling of the light. In the embodiment of Figure 3B, the depth of the display system can be less than half the focal length of the display system at maximum magnification.

[0070] Figures 3C and 3G each show perspective views of an embodiment using multiple seed (display) panels (1) to generate multiple depth layers. In Figure 3C, a beam splitter (120) can include photochromic layers (12, 13, 16, 17) for higher-order reflections within the cavity, and in some optical paths, the light beam can be directed directly toward the observer or reflected by a curved back reflector (121) (e.g., a mirror (3) placed on a free-form optic (4)). Light from the lower seed panel (1) passes through pre-cavity optics (9, 10, 27, 29) and is reflected directly by the beam splitter 120 to post-cavity optics (27, 10, 8), and then passes through a shield layer (122) toward the observer. Light from the upper seed panel (1) passes through the pre-cavity optics (10, 27, 29) and is first reflected by the beam splitter 120 towards the curved back reflector (121). The light then reflects off the back reflector (121) and passes through the beam splitter (120) before passing through the post-cavity optics (27, 10, 8) and shielding layer (122) to the viewer.

[0071] Figure 3D shows a perspective view of an alternative FEC embodiment in which 1D-1D curved optical surfaces (22) or DOEs, holographic optical elements (HOEs), metasurfaces, or Fresnel components (14) are introduced into the FEC design as an alternative method of control to independently control the wavefront of light traveling within the cavity, providing independent wavefront control in the vertical direction. This approach reduces complexity and allows for greater manufacturing tolerances than using a single 2D optical component with similar optical functionality and performance. Such 1D-1D architectures also allow for the use of thinner layers, significantly reducing the effective weight of the components.

[0072] In Figures 3D and 3G, light travels upward from the seed display panel (1) at the bottom of the cavity, passes through pre-cavity optics (10, 27, 29) and a beam splitter (126), and is then reflected downward by a first one-dimensional (1D) reflector (22) located at the top of the cavity. The light is then reflected toward a second 1D reflector (22) located at the back of the cavity and oriented perpendicular to the first 1D reflector. The light then passes through the beam splitter (126), post-cavity optics (27, 10, 8, 27), and a shielding layer (128) toward the observer. The combination of the two reflections from the perpendicular 1D reflectors acts as a combination of two cylindrical lens components, providing the desired 2D convergence or divergence to the wavefront.

[0073] In some embodiments, a 1D-1D curved reflector is one in which the reflector is physically curved in one dimension and has a surface grating or DOE variation in the perpendicular dimension that collectively function as a freeform 2D surface. The light then exits through a view aperture that is covered by a shielding layer (8, 27, or 48) from the outside world. In some embodiments, the back reflector is 2D, but the layer stack (37) can be 1D, meaning that the layer stack (37) is curved in one dimension. This allows the user's head to be lowered further into the aperture, thereby providing a wider field of view.

[0074] In the embodiments of Figures 3A, 3B, 3C, and 3D, the beam splitters (110, 117, 120, 126) can each have an anti-reflection layer (27) on the light transmitting side, and in the embodiments of Figures 3A, 3B, 3C, and 3D, the shield layers (112, 118, 122, 128) can each include an absorbing polarizer (8) coating and an anti-reflection layer (27).

[0075] FIG. 4A is a block diagram illustrating common system processing building blocks that can be used to render either 2D or 3D content into a display system according to an embodiment of the present disclosure. The display system is controlled by a computer and a synchronization ("sync") circuit. Any existing 2D or 3D content is processed by the computer (if necessary) and passed to a light source block. This processing may be to geometrically distort the image, or to mask the image of multiple panels so that it appears as a larger image to the viewer after viewing through the optical system, providing a better field of view, or to fit all four corners of the image into the viewer's field of view depending on the viewer's position in front of the display. This processing may be to provide multiple layers of information at various depths. This sub-block includes a content engine that performs the processing and a depth control sub-block that sends signals to the synchronization circuit. The synchronization block has two sub-blocks: one sub-block is a sensor that can read light signals from the video stream being displayed on the emissive display, and the other sub-block is a control circuit that commands the dimming mirror stack to control the light path (and consequently, the depth of the displayed image). This light source can be any one of a number of light sources or a combination of multiple light sources. As shown in the block diagram, this is an emissive display, so it can rely on any image creation technology, such as OLED, LCD, or LCoS, and can be 2D, autostereoscopic 3D, or any type of emissive display. Before being guided into the cavity, the light produced by the emissive display is processed by pre-cavity optics to prepare the light for directing to the rest of the system. These pre-cavity optics may manipulate the polarization, directionality, intensity, color, or wavefront of the light. Once the light enters the cavity, it travels one or more round trips using intra-cavity optical components that are geometrically shaped or patterned with structures to affect the light's wavefront.The light path can be modulated using a dimming device, and the wavefront can be shaped using any designed optical components. The light then exits the cavity where it is processed for optimal display. This light passes through an exit pupil and is directed to the user. Throughout operation, the display system is synchronized with a computer that generates or plays back the content. The block diagram shows representative examples of components for each block, and these components can be used in any combination.

[0076] FIG. 4B is a block diagram illustrating general system processing building blocks used to capture and record 2D or 3D image content from an external scene according to an implementation of an embodiment of the present disclosure. Light enters the system through an aperture and is processed before entering the cavity. A combination of intracavity optics and a photochromic device redirects the light along different paths within the cavity. The light then exits the cavity and undergoes post-cavity optical filtering, after which it is recorded by one or more sensors and digitized and sent to computer memory. Here, the computer directly controls the synchronization circuit block to program or process the light paths within the system. The different light paths can affect the optical zoom, focal plane, and illumination of the imaging system. The synchronization circuit ( FIG. 4B ) of the imaging system has two main sub-blocks: a synchronization sensor, which is triggered by an external signal entering the camera or directly by the computer and is itself a trigger control circuit; and a control circuit that can affect the photochromic mirror, optical components that affect the wavefront, and settings of the imaging sensor. The block diagrams show representative examples of components for each block, and these components can be used in any combination.

[0077] 5A-5K show a series of display embodiments or embodiment variations using a light-controlling stack corresponding to the embodiments of FIGS. 3A and 3E. In the embodiment of FIG. 5A, light is emitted by an emissive display (hereinafter collectively referred to as 49) with optional pre-cavity optics such as microcurtains, waveplates, and AR coatings through a beamsplitter (19) with an anti-reflection layer (27) to a light-controlling stack (37). The light is then reflected to a curved reflector (3, 4), passes twice through a QWP (10) to shift its polarization, and passes through an absorptive polarizer (8) and the anti-reflection layer (27) to the user (51), increasing the headbox size from (52) to (53). Here, the first reflection from BS 17 goes directly to the shielding layer and is absorbed by the absorptive polarizer, so it is not visible to the viewer. In some embodiments, a computer takes 2D or 3D content (54, 55) and estimates the optimal depth layer corresponding to that content through an optimization program that minimizes error. For example, some 3D content is provided with a game engine that has characters in a foreground layer, a middle ground in a middle layer, and an optically deep background environment in a background layer. Atmospheric particles (55) displayed in the game or 3D environment are displayed in all three layers to give the user a sense of depth. This is done through depth thresholding, so that the various cameras in the game engine or 3D environment engine only render a certain range of depth that matches the expected optical distance generated by the display. In some embodiments, processing software may convert 2D content, such as videos, games, photos, any 2D images, or text, into a multi-focal view using depth filtering techniques. In such techniques, images are first passed through an object segmentation algorithm. They are then passed through a depth estimation algorithm, and various objects are tagged or binned into the desired individual depth layers. In some embodiments, different layers (54) may be provided by entirely different content sources or different computers.In some embodiments, annotations in the foreground layer may be generated based on content shown in the deeper layers, such that the foreground layer becomes an augmented reality-like experience relative to the deeper layers. In these embodiments, the deeper layers are based on a master application executed by the user's personal computer, while the foreground layer is generated as an annotation layer by another application that reads input on the first master application and suggests or recommends content depending on the master application activity. In some embodiments, the computer displays content on different layers based on a best depth estimate of the 3D or 2D content and an optimization program that fits the 3D curvilinear layer to its depth profile with minimal error.

[0078] Figure 5B shows an exemplary embodiment of this light control stack family. Here, a display (1) can emit light that passes through a continuous polarization rotator material (56). The polarization retarder continuously rotates the polarization angle of light passing through it. This is a variable polarization control layer that imparts desired increments to the polarization angle. In some embodiments, this layer can be meshed or gridded to control the polarization of each pixel or a desired subset of pixels. The light then passes through a beam splitter (19) and is reflected by a monolithic birefringent reflector (57), where light of different polarizations experiences different optical thicknesses and therefore travels different optical depths. The monolithic birefringent material can be two crossed polarizers (8) or a stack of polarization-dependent reflectors. Polarization modulation can be varied across different pixels within one frame of the display, and it can be modulated for specific pixels over time. After reflection, it reflects off the beam splitter (19), then the curved reflectors (3, 4, 10), and finally passes through the post-cavity optics and shielding layer (48) before reaching the user. The polarization of the emitted light can be arbitrary (58). Similarly, as shown in FIG. 5C, some embodiments can operate in a transmissive mode and emit light from the display (1) into an electrorefractive or photorefractive layer (59). This can modulate the local or global refractive index using electrical or optical signals, and then send this light to the beam splitter (19). In some embodiments, the electrorefractive or photorefractive layer (59) can be modulated by signals within the display content itself to change virtual depth. As this light is reflected by the flat mirror (3), it experiences a round trip by passing through the electrorefractive layer (59) a second time. The beam splitter (19) redirects the light to the rear curved reflector (3, 4, 10), which then transmits the light through post-cavity optics and a shielding layer (48) to the user.In some embodiments, the electrorefractive or photorefractive material (59) may be replaced with an FEC with a Faraday rotator designed to make the light travel a polarization-dependent number of round trips before exiting the cavity.

[0079] The embodiment shown in Figure 5D is similar to that shown in Figures 5B and 5C, but includes a dimming stack (37) or LC layer stack (12, 13) composed of a mesh grid (60) or multiple mesh grids (60) with the same or different periodicities. These stacks can be individually dimmed so that different pixels experience different depths. The grid layers can have the same resolution or different resolutions to produce different retardation profiles. Light travels from the display and pre-cavity optics (49) through a beam splitter (19) to the grid (60), where it reflects back to the beam splitter (19), reflects off the curved reflectors (3, 4, 10), and then through the shielding layer (48) to the user. Some embodiments can emit light from the display (1) through a transmission grid (61), shown in Figure 5E, instead of the reflector grid (Figure 5D). This may include an LC stack (12, 13) that provides a parallax barrier and generates stereoscopic vision, allowing the left and right eyes to see different pixels at different angles. In this embodiment, the display can be any type of autostereoscopic display. Light passes through a grid and beam splitter (19), is reflected by a QM (31) onto curved reflectors (3, 4, 10), and is transmitted to the user through a shielding layer (48).

[0080] In the embodiment shown in Figure 5F, after the display emits light through a lenslet array (43) or other angular profiling layer (11), the light is collimated and then propagates through a stack of dimming diffusion / transmission grids (62). When the grid elements are turned off, they are transparent. When turned on, they act as a screen, and light striking them generates a point light source at that specific location. By changing the on / off position of the elements, the depth of the point light source for each pixel can be varied. The light then travels through a beam splitter (19) to a QM (31), a curved reflector (3, 4, 10), and a shielding layer (48) to the user. This flat mirror lengthens the display's optical path to the curved reflector, reducing the required curvature of the reflector. This increases the headbox area.

[0081] In Figure 5G, light is emitted from the display (1), and an electrically controlled liquid crystal HWP (9) can rotate the polarization of the light. The light strikes the PBS (20). When the HWP is ON, x-polarized light experiences a first reflection from the PBS (20) and passes directly through the shielding layer (48) to reach the user. When the HWP is OFF, the light is converted to y-polarized light, passes through the PBS (20), and is reflected by the QWP (31), which rotates the polarization by 90 degrees and converts it back to x-polarized light. At this point, the light can no longer pass through the PBS (20), so it is reflected by the PBS (20) and then by the curved reflector with the QWP, which rotates the polarization by another 90 degrees, turning it back into y-polarized light, which then reflects it back to the PBS (20) and finally through the shielding layer (48) to be directed toward the user. This first and second reflection corresponds to two layers (54) at different depths.

[0082] As shown in FIG. 5H, in most embodiments, the curved mirror can be replaced by a semi-reflective curved mirror or a thin lens or a group of thin lenses (19, 4, 10) that can be placed near the user and the head box to expand the field of view. In this figure, the dotted box (63) represents any display (1), or a plurality of display elements (1), a retroreflector (18), an LC layer, and any FEC or other cavity configuration including a beam splitter (19). The semi-reflective curve can function as a composite reflector in combination with a PBS (20), an absorption layer (8), and an antireflection layer (27). Here, the upper display and the rear display have absorptive polarizers that absorb unwanted internal reflections of other displays. The light from the rear display passes through the front lens and then through the PBS (20) and exits the cavity. The upper display emits light downward, and half of the light passes through the PBS (20) and is reflected vertically polarized from the surface of the lower display. Then, this is reflected towards the semi-transparent free-form optical component and emitted to the outside world. The light from the lower display rises as it is and is emitted towards the outside world by the PBS (20). In the lower display, the length P1, the length P2 of the rear display, and the length P3 of the upper display are created such that P1 < P2 < P3. After the free-form optical component, the view images will appear at three different depths that are significantly different from each other. In most of the embodiments and sub-embodiments of FIG. 3, in order to combine images from multiple displays, the reflector can be replaced by a segmented reflector so that the lines between the smaller displays are removed or hidden, resulting in a larger optically integrated continuous image with a larger FoV (see Patent Document 5 and Patent Document 6. These are incorporated into the present application by reference).

[0083] FIG. 5I illustrates an embodiment in which multiple OLED or thin flexible displays (64) or curved displays (5, 49, 64) and / or reflective mirrors or QMs (31) can be mechanically shifted by vibrating coils or optionally designed actuators or actuator arrays (15) that locally or globally change depth, thereby changing the physical path of light. In this embodiment, the PBS (20) can include an anti-reflection layer (27). After the light reflects off the curved reflectors (3, 4, 10) and passes through a beam splitter, the light passes through another PBS (20) and an anti-reflection layer (27) that minimizes stray reflections before reaching the user. In some embodiments, as shown in FIG. 5J, multiple dimming EORS stacks (37) can be placed after each of the multiple displays and pre-cavity optics (49), each comprising a semi-transparent curved mirror or thin lens or lens group (19, 4, 10) and a PBS element (20, 8, 27). Light from one display travels through the associated stack and is reflected by another display stack, and both paths travel to a curved semi-transparent mirror containing QWPs (10) on both sides and are then combined into a segmented or curved PBS (20) that acts as a composite reflector.

[0084] Figure 5K shows an embodiment with two orthogonal displays (1) each having a dimming LCD layer (12, 13) and a semi-reflective surface coating. When both LCs are OFF, the light from the rear display passes through the PBS and exits to the outside world (optical path P1), and the light from the lower display travels upward, reflects off the PBS, hits the surface of the semi-reflective rear display, experiences polarization rotation by the QWP at the top of the rear display, and passes through the PBS and exits to the outside world (optical path P2). When the LC of the rear display is ON, the light hits the PBS and travels downward and upward, but since there is no QWP in the lower display to properly rotate the polarization, the light still cannot exit from the PBS. The light then has to return and hit the surface of the rear display again. In this case, the light experiences a 90-degree polarization rotation by the QWP and can now pass through the PBS (optical path P3). These three light trajectories follow the optical paths P1, P2, and P3 such that P1 < P2 < P3. For the observer, this results in a depth of three layers. Since this embodiment does not have lenses or curved optical components, the observer can view the depth with an infinitely large head box. This is suitable for, but not limited to, in-vehicle or dashboard applications, which will be further described below.

[0085] Figures 6A-6K show a series of embodiments of displays with compressed cavities, corresponding to the embodiments of Figures 13B and 3F. In general, surfaces can be macroformed so that their shapes can be arbitrarily designed in one or two dimensions. The macroformation can be static or time-varying, such that mechanical waves travel across the surface and shape it spatially and temporally. The macroformation can be temporally modulated using mechanical actuators, ultrasonic actuators, or other actuators that use acoustic waves, or electronically modulated. As shown in Figure 6A, the compressed cavity effectively moves the curved reflector closer to the user and increases the headbox size from a small size (52) to a large size (53), which increases the field of view compared to an expanded cavity. However, the object distance (optical distance from the display to the curved reflector) remains long. Light of arbitrary polarization (58) travels through the pre-cavity optics (47) from the display or another cavity. Here, light is reflected by the beam splitter and anti-reflection layer (19, 27) to the curved reflector (free-form optics and mirror) (3, 4), then passes through a layer stack including an anti-reflection coating (27) and a shielding layer (48) to reach the user (51). Figure 6B shows another exemplary embodiment with a double reflector forming a wedge-shaped structure. Light from the display (1) reaches the observer only after multiple reflections, in the horizontal direction of the figure. Here, the optical depth increases with each reflection before hitting the curved reflector (3, 4, 10) with a QWP, which rotates the polarization by 90 degrees so that the light can pass through the tilted front reflector. Because the angle of the tilted reflector is less than 45 degrees to the vertical, the physical depth is shorter than the optical path length. Two baffles (48) act as shielding layers and prevent the user from looking directly at the display. The architecture is designed so that light from the display descends and hits the PBS, but initially the light cannot travel to the outside world.This light then travels toward an internal vertical, flat reflector and is reflected back toward the PBS; the PBS is still cross-polarized, and the light travels toward the curved reflector. At the center height, the vertical reflector is 100% transparent, so the light passes through it and hits the curved reflector with a QWP, which makes the polarization parallel to the pass angle of the PBS. The light passes through the PBS and exits to the outside world. In some embodiments, the gradient layer may be a reflective surface whose reflectivity varies with the angle of incidence.

[0086] Instead of a flat, static reflector, the embodiment of Figure 6C includes a macroformed anamorphic surface (65) that emits light from the display (1) and is excited by mechanical waves (e.g., ultrasound or acoustic waves) at a desired frequency and amplitude to generate reflection and transmission. The image is raster-displayed in synchronization with the waves traveling on the reflector. This material can be made from a polymer-based material such as PMMA, thin glass, or a combination of glass and polymer-based materials. The polymer-based material may have a semi-reflective coating or serve as a substrate for a thinner glass layer. The display has a raster-scanned or shadow mask, which deflects light rays at specific locations along various distances in synchronization with the surface waves on the anamorphic layer. The displayed image can be pre-distorted to compensate for distortions caused by the anamorphic surface at desired times. The light from the display (1) is x-polarized and reflected by the anamorphic beam splitter. The curved reflector includes a QBQ layer that rotates the polarization of light to y-polarized light for passage through the anamorphic beam splitter. Light from pixel t1 of the display panel travels a distance p1, as do pixel distance pairs t2-p2 and t3-p3. These rays strike the curved reflector (3, 4, 10) and pass through the shielding layer (48) to reach the user. The shape of the reflector (65) is configured so that its effective angle with respect to the horizon is greater than 45 degrees, but the location where the waves impinge is shallower so that the waves exit the cavity horizontally. The physical depth of the cavity is compressed while maintaining a wide field of view, as indicated by the wider separation between the rays traversing the shielding layer (48) compared to the separation of the rays at the display panel (1).

[0087] In some embodiments, by synchronizing the light emitted from the display panel with the movement of the anamorphic surface, individual pixels t1, t2, and t3 can be redirected to travel different lengths or to different positions relative to the user's eyes, creating a stereoscopic view or tuning monocular depth. In some embodiments, an angular profiling layer can assist in redirecting these light rays. The timing of the display and anamorphic reflector is controlled so that the curved reflector realizes a vertical reflection of the display, which can be higher or lower than the physical height of the display. This effect can be achieved by changing the timing or by increasing the amplitude and frequency of macro-forming waves on the surface of the anamorphic reflector.

[0088] Similarly, the embodiment of Figure 6D generalizes the concept of Figure 6C and includes multiple anamorphic surfaces (65) that function together as a waveguide or image guide. These surfaces are modulated with mechanical waves so that their surface shapes are complementary. Two tilting displays (1) couple light into the waveguides at angles such that light exiting the waveguides toward the curved reflector has a horizontal chief ray after two or more reflections to compensate for steep and shallow angles. In some embodiments, these waveguides are polarization-dependent and include shielding layers and reflective coatings (66) on different regions of the waveguide to increase efficiency. The top and bottom surfaces can be fully reflective to increase efficiency. The light can be of any polarization (58).

[0089] The embodiment of Figure 6E includes a plane-filling structure known as an orthogonal field evolving cavity (OFEC) (see Patent Document 5). A display (1) emits light, which immediately passes through a lenslet, lenticular lenslet, pinhole array (67), or other angular profiling element (11), which tilts the light from different pixels in different specific directions. A vertical mirror (3) guides the various light rays to a beam splitter (19, 27), which redirects the various light cones to different portions of a rear curved reflector (3, 4, 10). The light rays then travel through the beam splitter (19, 27) and a shielding layer (48) to the user, who sees a bundle of various cones coming from different heights. One cone of light generates an image I1, a second cone I2, and a third cone I3. Each of these sub-images can be combined, or vertically tiled, or tessellated to create a wider vertical field of view. Here, the image of each subset of pixels represents a specific tile or segment of the overall image, so the seed image should be interlaced with the various segments displayed on a high-resolution narrow panel at the core of the OFEC (see U.S. Patent No. 5,623,499). In some embodiments, the OFEC may have time-synchronized dimming polarization-based mirrors. An example of an OFEC and how to program it is described in U.S. Patent No. 5,623,499.

[0090] In Figure 6F, a single anamorphic reflector can be used with large-amplitude surface modulation. Total internal reflection at the edge (68) efficiently guides display light to the semi-reflective region (69). The light then reflects off the curved reflector (3, 4, 10) toward the user. Orienting the display vertically increases cavity compression. The curved reflector can include a QWP layer that rotates polarization by 90 degrees for polarization-dependent reflection. Instead of a modulated anamorphic reflector, the exemplary embodiment of Figure 6G uses a curved PBS (70) in front of the curved reflector (3, 4, 10) to effectively move the curved reflector closer to the user and expand the field of view. The beamsplitter (19) can be curved in one or two dimensions, but the effect of this curvature on the light should be compensated for or accounted for in the design of the complementary back reflector and seed image so that the net effect is the desired virtual image. The image on the display is therefore pre-distorted to account for and compensate for the distortion caused by the beamsplitter. The back reflector also exhibits vertical free-forming (4) that optically corrects the shape of the beamsplitter. The light emitted from the display is x-polarized and is reflected by the curved PBS. The curved back reflector contains a QWP layer that rotates the polarization by 90 degrees so that the polarized light can pass through the PBS and reach the user.

[0091] As shown in Figure 6H, the emissive display itself in most of these embodiments can be replaced by an arbitrarily designed FEC (71) with multiple displays to create multiple depth layers or enhance brightness. The dotted box can represent such a cavity. A vertical display does not reduce the compression of the embodiment, and this embodiment functions similarly to the other embodiments. X-polarized light is emitted by the FEC (71), reflected by the PBS (20), and then reflected by the curved back reflector (3, 4) with a QWP (10) that rotates the polarization. This light becomes y-polarized and passes through the PBS (20) and the shielding layer (48).

[0092] In some embodiments, such as that shown in Figure 6I, a rotating one-dimensional mirror (72) is used to create a two-dimensional lens with a tunable or rastering focal length. In Figure 6I, an emissive display (1) or projector emits x-polarized light, which is reflected by the PBS (20) through the QWP to generate circularly polarized light. This light is reflected by the one-dimensional rotating mirror (72) back through the QWP (10), resulting in y-polarized light that can pass through the PBS (20). This light then passes through another QWP (10), again generating circularly polarized light, which is then reflected by a second one-dimensional rotating mirror (72) oriented perpendicular to the first one-dimensional rotating mirror (72). The reflected light again passes through the QWP (10) and is finally converted to x-polarized light, which is reflected by the PBS (20) and reaches the user. Such an embodiment is ideal for components of microprojection or headset-based systems.

[0093] Figure 6J shows an embodiment of x-polarized light traveling upward from an emissive display with pre-cavity optics (49) through a steeply tilted PBS (20) at an angle greater than 45 degrees. The light then strikes a tilted QM (31), which reflects y-polarized light at an oblique angle. The light is reflected by the PBS (20) and then by the curved reflectors (3, 4) and QWP (10), which rotate the polarization back toward x-polarized light. The light is transmitted through the PBS (20) and shield layer (48). In some embodiments, the bottom emissive display may have an OFEC to provide a larger vertical field of view. In some embodiments, the top mirror may be a 1D or 2D convex mirror, which tunes the optical path and designs the desired vertical field of view.

[0094] Figure 6K shows a display in which a pre-cavity optic (47) emits x-polarized light. This light travels upward through a tilted beam splitter (19, 27) and is reflected by an EO reflector (33) that can be tilted at various angles, or by a stack of EO reflectors at various angles that become reflective and transparent at different times. The net result is reflected light beams at different time intervals and angles. Therefore, this embodiment can rasterize a narrow display with a larger vertical reflection relative to the curved back reflector. All light beams are reflected by the curved back reflector (3, 4, 10) and propagate through the beam splitter (19, 27) and shielding layer (48). In this illustration, the steepest tilt position of the EO reflector (33) corresponds to path t3. The shallowest tilt position corresponds to path t2. The shallowest tilt position corresponds to path t1. The combination of the named EO reflector (33) and steeply angled beam splitter (19, 27) allows for a thinner overall footprint while maintaining a larger vertical field of view.

[0095] Figures 7A-7F show a series of embodiments of multifocal and light field displays with multiple seed display panels, corresponding to the embodiments of Figures 3C and 3G. In Figure 7A, light of any polarization (58) travels up and down from an emissive display with pre-cavity optics (46, 47). Light from the lower display layer is reflected back to the user by a beam splitter and anti-reflective coating (19, 27), and light from the upper display layer is first reflected by a curved rear reflector (3, 4) and then emitted to the outside world. Both sets of light beams pass through a stack of layers (27, 10, 8, 27) before reaching the user (51). This results in multiple depth layers (54) being displayed to the user. In some embodiments, the lower display can be covered with an absorbent micro-curtain to block direct line of sight.

[0096] Figure 7B shows a similar embodiment in which the central beam splitter is replaced by a PBS (20) sandwiched between two dimming LCD layers (12, 13) that switch themselves between two modes. Two displays (1) can create a total of four layers deep. When the LCD layer is ON (12), the light emitted from both displays remains x-polarized (1). The light passes through a QBQ (30) stack laminated on top of the displays. The light is then reflected by the PBS (20). Light from the upper display is reflected by the back reflectors (3, 4) and the QWP (10), resulting in y-polarized light traveling through the PBS (20) to the user and corresponding to a distance P1. Light from the lower display is reflected directly back to the user and corresponding to a distance P2.

[0097] When the LCD layer is OFF (13), x-polarized light from the upper display (1) passes through the QBQ (30) again and is rotated by the upper LCD layer (13) to y-polarized light. This passes through the PBS (20) and the lower LCD layer (13), again emitting as x-polarized light. This strikes the QBQ (30) laminated to the lower display, which rotates the polarization to y-polarized light and reflects it upward; the light is reflected by the PBS (20) to reach the user, which corresponds to a distance P3. When the LCD layer is OFF (13), x-polarized light from the lower display (1) and QBQ (30) passes through the LCD-PBS-LCD layer (13, 20, 13) and is reflected by the QBQ (30) laminated to the upper display, which rotates the polarization and reflects the light downward. This light is then reflected by the LCD-PBS-LCD layer (13, 20, 13) onto the curved reflector and QWP (3, 4, 10), which again rotates the polarization and allows it to pass through the LCD layer (13, 20, 13); it exits the cavity and corresponds to a distance P4. A total of four depths can be generated.

[0098] Similarly, the embodiment of Figure 7C uses a liquid crystal layer and beam splitter at different orientations relative to the display and mirrors to create layers of different depths. When the LCD is ON (12), x-polarized light is reflected by the PBS (20) to the curved reflector with QWP (3, 4, 10), rotated to y-polarized light, and then returns to the PBS (20) and shielding layer (48). When the LCD is OFF (13), y-polarized light first passes through the PBS. At the bottom is a QM (31) reflector that converts the light to x-polarized light, which is then reflected by the PBS (20). These two optical paths allow the user to see two layers of depth.

[0099] In FIG. 7D, the curved reflectors (3, 4) are semi-reflective. In this embodiment, all the depths shown are curved and long in distance. Light from all the display panels (1) at the top, bottom, and back (or left side) of the cavity interacts, creating a virtual image at a longer distance. The upper display has a reflective layer for increasing the optical path. Light rays from the left and lower display panels are reflected by this layer before hitting the curved reflectors. The micro-curtains at the top and bottom of the display will prevent unwanted light from entering the user's eyes. Three representative optical paths show the relative distances. The y-polarized light (P1) from the left display panel (1) passes directly through the curved reflectors (3, 4), is reflected upward by the PBS (20), and then is reflected by the semi-reflector of the upper display. Then, this reaches the PBS, and since it remains cross-polarized, it returns to the back curved QBQ, causing the polarization to change and it is directed outwards through the PBS. The x-polarized light (P2) from the upper panel is first reflected by the PBS (20), then is reflected by the curved QBQ layer with the polarization rotated 90 degrees to become y-polarized light, and then passes through the PBS (20) and the shield layer (48). The y-polarized light (P3) from the lower display panel (1) first passes through the PBS (20), then is reflected by the coating of the upper display panel, and then follows the path of P2. In this exemplary embodiment, the distances are ordered such that P1 < P2 < P3, resulting in three depth layers for the user.

[0100] The embodiment of Figure 7E includes a projector or projector array display (74) in addition to the flat display panel (1). The projected light is y-polarized and then strikes a polarization-dependent diffuser (73), which acts like a transparent display layer. The diffuser layer can be monolithic or a grid with individual dimming grid elements. The light is reflected by a beam splitter (19), then toward the curved reflectors (3, 4), and passes through the shield layer (48). Light from the flat display panel (1) is reflected by the beam splitter and then by the curved reflectors (3, 4, 10), which rotate the light to y-polarized light and transmit it through the beam splitter. The lower projector array can be computationally synchronized with the images projected from the upper display so that autostereoscopic viewing is provided, or higher dynamic range is created in the image, or glittering effects such as sparkles or glitter in the scene can be represented or amplified, it can provide a light field, or different images can be seen from different angles.

[0101] The embodiment of Figure 7F is an example of an X-shaped architecture with multiple seed displays (1) and LC layers (12, 13). Light from the upper layer is polarized perpendicular to the light from the lower layer. Two PBS (20) layers are oriented so that they reflect and transmit light of opposite polarizations. In the ON mode, light from each display (1) passes through the closer PBS layer (20). Each is reflected by a back-curved QM reflector, which rotates the polarization so that the reflected light passes through the associated PBS (20) layer and then through the shield layer (48). In the OFF mode, the polarization of light from the display (1) is first rotated 90 degrees and then simply reflected by the first PBS reflector (20) to the shield layer (48). In some embodiments, optical fusion mechanisms such as invisible bending and computational masking may be used to fuse images from different segments without bezel lines or center seams (see Patent Document 6).

[0102] Figures 8A-8P show a series of display embodiments (1D-1D architectures) with multiple one-dimensional elements that mimic or affect light in a two-dimensional lensing manner, corresponding to the embodiment of Figure 3D. These elements can be macroformed in one dimension and uniform in another. They can also be fabricated in a hybrid 1D-1D manner, where elements are macroformed in one dimension and have structural variations in the other. These structures can include 1D metasurface layers, diffraction gratings, or Fresnel lens-like structures. For example, the embodiment of Figure 8A includes two one-dimensional geometric bends with curvatures in the perpendicular direction. The resulting embodiment focuses light in two dimensions and approximates a 2D bend. Light of any polarization (58) travels upward through several pre-cavity optics (46), passes through beam splitter layers (19, 27), and then reaches the first 1D bend (22). It is then reflected by the beam splitter layers (19, 27) toward a second 1D flexure (22) oriented perpendicular to the first 1D flexure. The light then travels through the beam splitter layers (19, 27), the post-cavity optical layers (27, 10, 8, 27), and finally to the user (51). This design increases the object distance while decreasing the curvature of the curved optics, thereby increasing the headbox from (52) to (53). Similarly, the embodiment of Figure 8B includes a 1D curved display (5), a curved mirror (22), and a curved beam splitter (22). This shape can be tuned relative to the absorber (28) and the shield / post-cavity layer (48). Light (58) of any polarization is emitted from the curved emissive display (5) (which in some embodiments can be an OLED or POLED), reflected by the 1D curved beam splitter (22), reflected by the 1D curved reflector (22), and sent to the post-cavity optics (48). The absorbing layer (28) removes stray light.

[0103] In the embodiment of Figure 8C, the curved display (5) emits light (58) of any polarization, which is reflected by a curved beam splitter (70) onto a 1D curved reflector oriented perpendicular to the curvature of the display. The light is reflected towards the curved beam splitter (70) and the shielding layer (48). The curvatures are designed so that they emulate a single 2D curved reflector.

[0104] As shown in Figure 8D, light can be emitted from the display (1) and passed through a polarizing 1D curved beam splitter (70) and a 1D curved semi-reflector (22), all coaxially. The polarizing layer changes the polarization of the light as it makes its round trip through the cavity. Circularly polarized light is emitted by the display (1), converted to y-polarized light by the QWP layer on the curved semi-reflector (70), and reflected by a second curved reflector (22) oriented perpendicular to the semi-reflector. After the second reflection by the semi-reflector, the light is rotated to x-polarized light, allowing it to be sent through the 1D curved PBS reflector (22) toward the outside world.

[0105] In the embodiment of Figure 8E, the one-dimensional layer can be curved, i.e., have a geometric structure, in one direction, and have a surface structure in the perpendicular direction (75). The structure can be a lens structure or a diffractive structure, and can include, for example, a DOE (14), a Fresnel grating, or a metasurface. In this embodiment, light is emitted from two display panels (1) with reflective coatings and travels to a 1D-1D hybrid structure (75) and toward the post-cavity optics (48). Similarly, as shown in Figure 8F, both 1D-1D structures can be Fresnel diffractive structures. Light travels from the display panels (1) to two 1D surfaces (76) oriented perpendicular to each other and then to the post-cavity optics (48).

[0106] The embodiment of Figure 8G includes a QWP with a curved display (5) and a two-dimensional curved mirror (4) that guides the light's round trip. This embodiment can also have an additional free-form layer (77), which can be a Fresnel layer, a diffractive layer, or a metasurface. This latter free-form layer compensates for the geometric curvature of the layer so that the end result is effectively an optically flat surface. For example, a concave 2DPBS layer facing the user could have a metasurface or diffractive optic on top of it that has the opposite optical power as the convex surface, making it optically natural or flat in reflection or transmission. This allows the system to be thinner, move closer to the curvature of the user's face, and provide a wider field of view. The emitted light is circularly polarized, converted to y-polarized light by the central element (4), reflected by the free-form or metasurface (77), converted to x-polarized light on the second reflection (4), and presented to the user by the free-form or metasurface (77).

[0107] Figure 8H shows an embodiment with a flexible emissive display (5). This display can be an OLED or POLED display, or any flexible emissive display, and the display surface is modulated with mechanical waves of various frequencies and amplitudes. The 1D curved display transmits light to the PBS (20) through a hybrid 1D-1D structure (78).

[0108] In some embodiments, the 1D-1D structures are anamorphic and can be modulated with mechanical vibrations of various frequencies and amplitudes. These can be modulated in the same way as the display modulation, allowing them to be synchronized with the display modulation. The modulation can tune the physical depth of the display and the directionality of light across the image. For example, the embodiment of Figure 8I uses two anamorphic 1D surfaces oriented perpendicular to each other and modulated with surface waves (79). These reflect light from a curved reflector (3, 4, 10) with a QWP, which changes its polarization and allows it to be transferred to the post-cavity optic (48). X-polarized light is reflected from the anamorphic layer, converted to y-polarized light by reflection from the curved reflectors (3, 4, 10), and transmitted to the anamorphic layer and shield layer (48).

[0109] Similarly, in Figure 8J, arbitrarily polarized light (58) passes through a planar beamsplitter (19), reflects off two 1D-1D anamorphic surfaces vertically modulated with surface waves (79), and propagates through post-cavity optics (48) to the user. This embodiment produces the desired autostereoscopic and monocular depth profile. In some embodiments, this profile may be varied based on input from a head-tracking or eye-tracking device.

[0110] In the embodiment of Figure 8K, the display (1) and anamorphic surfaces (80, 81) can be arranged in a coaxial configuration in a transmissive mode with polarization-dependent coatings or surfaces. The display can include a moving shadow mask synchronized with the anamorphic surfaces to eliminate unwanted stray light and undesired artifacts. Circularly polarized light passes through the first anamorphic layer; the second layer reflects the light, converting it to y-polarized light at the QWP layer, which reflects again at the first anamorphic layer. This is finally converted to x-polarized light and exits the cavity.

[0111] In the embodiment of Figure 8L, the display is curved in only one dimension (5) and emits light into a hybrid 1D-1D element (78). This element is geometrically curved in the same direction as the display, but in the vertical direction, it has a Fresnel grating, metasurface, or diffractive optical structure so that the structure appears as a 2D surface to the display light reflected from the front PBS layer. The outer PBS layer also includes a free-form metasurface or diffractive element (77). This composite structure, similar to the embodiment of Figure 8G, is designed to resemble a flat surface without sacrificing the field of view. Light returns to the hybrid 1D-1D structure and is transmitted to the outside world. The result is an extremely thin (thinner than Figure 8G) virtual display, light field display, or multifocal display that curves in front of the user and has only 1D geometric curvature. In some embodiments, the display may be covered with a flexible LC layer that switches the polarization of the light, thereby creating multiple layers of depth.

[0112] Instead of guiding light along a structure, some embodiments, such as that shown in Figure 8M, can include a curved display with segmented one-dimensional curvature (5). These segments are sequentially raster-scanned (switched between reflection, absorption, and transmission) to guide light in a non-coaxial manner. LC layers with PBS elements can manage unwanted reflections or light leakage by turning gates / segments ON (total reflection) and OFF (fully transparent) or absorbing (82, 83). Light is guided along preferential paths to improve light throughput efficiency. Pixels can experience one round trip (t1) or multiple round trips (t2) before exiting the cavity. In some embodiments, these layers can be one-dimensional Fresnel structures and vertical geometry semi-reflectors (hybrid 1D-1D semi-reflectors).

[0113] Figure 8N shows an embodiment in which two 1D-1D pairs are oriented so that light is reflected twice by them. The display panel (1) emits y-polarized light into the polarizing curved semi-reflector (70). This is done in two segments: an upper segment and a lower segment. In some embodiments, more segments may be used. After reflecting from the post-cavity optics (27, 20, 8, 27), the light's polarization is rotated and it reflects back from the shield layer. It is then reflected perpendicularly by the polarizing curved semi-reflector (70) to a vertically oriented 1D curved reflector (22). These change the polarization (31) and reflect the light back to the curved semi-reflector (70). The reflected light travels through the post-cavity optics (27, 20, 8, 27) to the outside world. The upper and lower 1D reflectors can be macroformed or moved by actuators (15) to control their depth. The polarizing optics allow the light to become x-polarized and be reflected by the curved beamsplitter and pass through the post-cavity optics. The double reflection from the central curved semi-reflector reduces the curvature of these reflectors, thereby increasing the headbox.

[0114] In the embodiment of Figure 8O, the display (1) is vertical and emits light (58) of any polarization toward the left. Here, the light is reflected by a one-dimensional mirror (22) into a light pipe with one side curved (22) perpendicular to the first mirror. The curvature of the first mirror is tuned to compensate for the varying distance traveled by light emitted from various parts of the display. The light then passes through glass, a prism grating (84), or a film with angle-dependent reflectivity to reach the user (51).

[0115] Finally, the embodiment of Figure 8P shows two displays that guide light rays between two curvatures. These curvatures can be microformed surfaces (80, 81) in x and y, macroformed surfaces, segmented, or a combination of these elements so that light exits and travels from a central region. Light is directed to the user (51) after two or more reflections between the back (left side) and front (right side, closer to the user's face).

[0116] The embodiments of Figures 5A-5K increase headbox space by folding object distance through double reflection of light within the cavity. Figure 9A shows a cramped headbox in which light is reflected by a single curved reflector. Because eye distance is very short, the user must remain fixed in a small spatial area in front of the display system. In contrast, in Figure 9B, multiple reflections from the display system of Figures 3A-3D with curved reflectors significantly expand eye distance (e.g., to about 50 cm) while maintaining the same magnification as Figure 9A. The headbox space is longer for more relaxed viewing.

[0117] Further analysis is shown in Figures 10A and 10B, which are perspective and side views, respectively, of a ray diagram for a 1D-1D cavity. Light is emitted from the display and pre-cavity optics (46) into beam splitter layers (19, 27), and 1D bends (22) are located on the top and back of the display system. Due to the point spread function of the example 1D-1D cavity, aberrations are minimal and nearly symmetrical within the visible zone for the user.

[0118] 11A-11C show schematics for fabricating several subsampled Fresnel lens diffractive structures. FIG. 11A is a schematic of such an element in single-pass transmission mode. FIG. 11B adds a reflective layer to the substrate in refractive mode so that light passes through the structure twice. FIG. 11C shows a reflective coating on top of the diffractive structure. Such diffractive 1D structures can be implemented using continuous phase profiles or subsampled phase profiles.

[0119] Additional embodiments are shown in Figures 12A-12D, where the technology introduced above can be implemented in portable applications, including headsets, autonomous vehicle displays, and handheld devices. In a headset device, a display (1) emits a beam of light that is reflected off a cavity beam splitter surface (19, 27) and then off a single monolithic 2D bend (22). This light passes through post-cavity optics and shielding layers (10, 8, 27) and provides the user with an extended head zone. Unlike other headsets, here, the left eye's field of view (eyebox) overlaps with the right eye's field of view, and polarization separates the views from each eye. This significantly improves image accuracy and reduces the nasal occlusion area present in headsets with two separate eye channels from separate displays. In an alternative embodiment, the display emits light that is reflected by beam splitter surfaces (19, 27), then by mirrors and freeform optics (3, 4), and then through post-cavity optics and shielding layers (10, 8, 27) before being directed toward the user. An absorption layer (28) filters out stray light. Similarly, the display can emit light that first propagates through several pre-cavity optics (27, 10, 29), then is reflected by beam splitter layers (19, 27), and then passes through a 1D bend (22) toward the post-cavity optics and shielding layers (10, 8, 27).

[0120] As shown in Figures 12A and 12B, different polarizations can be delivered to different eyes, providing both monocular depth cues and stereoscopic vision without the need to tune the user's interpupillary distance. The polarization is switched by an LC layer on a high-frame-rate display so that frames are sent alternately to the left and right eyes. In both figures, the emissive display may be arbitrarily designed. It may be curved, autostereoscopic, macroformed, or have FEC or OFEC on or around it. The difference between Figures 12A and 12B is that in Figure 12A, light from the emissive display goes to a PBS or beamsplitter and curved reflector, and there is only one monocular depth, gated based on the layer in front of each eye, whereas in Figure 12B, the display is at the bottom and a switchable mirror stack is on top, which not only increases the eyebox but also provides multiple monocular depth layers on top of the perceived stereoscopic vision, much like the embodiment in Figure 3A. This is achieved by performing polarization gating at the front layer near the eyes and generating a global light field with a large binocular overlap region.

[0121] All of the embodiments shown in Figures 3A-7F can also provide left-eye / right-eye images in a headset format by using alternating polarization and gating the polarization for each eye with polarizing elements (10, 8, 27), as shown in Figures 12A and 12B. In some embodiments, the polarization does not change in time at all and may be provided by two displays that insert light with perpendicular polarization into a beam splitter positioned as an input-emissive display within an enclosure similar to the enclosure (71) in Figure 6H. This eliminates the need for temporal switching, as all layers are passive. In Figure 12C, multiple gates are controlled by a head- or eye-tracking camera (85) to shift x-polarized light and y-polarized light across the entire visible zone. An example of this imaging is shown in Figure 12D. Here, the left and right eyes see slightly different images, and the user experiences parallax, or stereopsis. The size of these vertical segments varies depending on the desired headbox. These vertical segments are EO shutters (32), which switch in synchronization with the left-eye / right-eye frames displayed on the display, depending on the interpupillary distance of the user's eyes. This mechanism also allows the images in Figures 3A-7F to provide left-eye / right-eye images, providing multiple monocular depths for stereoscopic viewing.

[0122] 13A shows an exemplary embodiment for use in an automobile or other type of vehicle for entertainment. Inside the vehicle 86, the display system can be folded into the roof or passenger compartment of the vehicle. The mechanical support (87) for the display system can be a folding arm that can extend telescopically or move up and down so that the display system (88) can be moved to a comfortable area for the viewer, in this example, a passenger (89).

[0123] Figure 13B illustrates the application of the above-described techniques to a portable device such as a smartwatch (90), where different content layers (91) can be generated such that the layers appear deeper than the watch's physical aperture (90) or the image appears to float above the physical object, all through a combination of monocular and binocular depth mechanisms provided by the device. These techniques may be used to create a 3D image or multi-depth perception of the mechanical hands of a classic watch, or to create a multi-depth user interface (92) for answering calls or interacting with the smartwatch in any application. Element (93) is the watch body, element (94) is the driver board, and element (95) is an emissive display. In some embodiments, the display may be macroformed; in some embodiments, the display may have a functional coating to enhance the light efficiency of optical layers deposited on the display. Elements (96) and (101) are transducer arrays for 1D macroforming of the QBQ layer, and elements (97) and (99) are transducer arrays for 1D macroforming of the PBS layer in a direction perpendicular to the deeper QBQ layer. The transducers can be mechanical transducers, such as piezoelectric transducers, magnetic coil arrays, or capacitive transducers, or a combination of these. Between the QBQ and the PBS is a buffer PMMA or transparent elastic polymer layer. Element (98) is a protective, durable touch glass covering the system. Element (100) is a function button for interfacing with a watch or smartwatch, which can be used to modulate the transducer arrays (96, 97, 99, 100) or the electro-optic layer for programmable / tunable depth of the displayed image. The same or similar architecture can be used in any application for smartphones, tablets, televisions, or other displays. For smaller devices, this approach is more appropriate since the shorter distances between the macroformed layers result in lower losses.

[0124] FIG. 13C illustrates how the technology introduced in this disclosure impacts an in-vehicle dashboard application. Here, element 102 is a car's odometer or digital interface layer. Element 90 is a virtual image layer embedded in a display system remote from the vehicle driver or operator. These images appear to the driver to be located in a deeper layer beyond the display's physical location. In some embodiments, the disclosed methods can be used to create two or more layers of depth for an in-vehicle tablet interface, such that interaction buttons appear to protrude from or be embedded in the touchscreen 152. In some embodiments, the car's odometer may appear closer than a map, or a multi-layer interface may be displayed on the odometer raster. In some embodiments, the layer depths may vary significantly, with a closer layer being centimeters away from the user while a deeper layer is optically several meters away. This imbalance reduces eye fatigue or eye tuning as the driver alternates between looking at the road and the dashboard.

[0125] All displays, architectures, and systems can be made translucent by tuning the reflectivity of the curved rear reflector in the disclosed architectures or by projecting the output of the viewing aperture onto the windshield. Multilayer display types (42) or (50) FECs can be curved behind tablets or inserted into the front of dashboards to hide the device's size or add depth without adding curved or freeform elements. In some embodiments, a retroreflective layer may be used or deposited on the surface of the emissive display to make the image appear to protrude from the aperture rather than sink into it. In all embodiments, the optical distance from the freeform or lens element may be longer than the focal length to make the image appear to float in front of the aperture rather than sink into it. In automotive applications, instrument clusters with such hovering or protruding images may be used for touchless interfacing with the vehicle.

[0126] FIG. 14 illustrates a process associated with the techniques presented in this disclosure for generating a 3D image in a display system. In step 141, the process emits light from one or more displays within the display system. In step 142, the process dynamically controls the path length traveled by the light emitted from at least one display within the display system by directing the light at multiple reflective surfaces within the display system. As a result, light rays corresponding to different virtual images travel paths of different lengths within the display system, forming multiple virtual images that simultaneously appear to a viewer at multiple different optical depths. It will be appreciated that a process similar to that shown in FIG. 2 is performed. It will be understood that steps similar to those shown in FIG. 14 can be performed by a camera or other imaging sensor to capture a 3D image of a scene, omitting step 141.

[0127] Any of the above-described embodiments including a segmented display can be worn as a headset, as shown in Figures 15A and 15B. The headset (103) can be used for transparent or see-through augmented reality (AR) applications as well as occluded virtual reality (VR) applications. The headset provides both monocular and stereoscopic depth and has a continuous, unseparated aperture (104) for each eye. This continuous aperture increases binocular overlap and eliminates nasal occlusion. Furthermore, interpupillary tuning is not required. The headset (103) can have a strap (105), such as an elastic strap, worn around the viewer's head and can include a comfortable fit guard (106) to reduce fatigue. The strap is adjustable. Embodiments using the 1D1D mechanism described in Figure 8, particularly Figure 8K, can be implemented to reduce thickness. An outward-facing camera (107) can also be added for spatial localization and mapping functions, as shown.

[0128] In some embodiments, as shown in Figure 15C, a user (51) can wear headphones and a microphone (108) that interface with a headset or communicate wirelessly with other users. In some embodiments, the headset can have an eye-tracking camera and / or gesture sensors that allow the user to manipulate virtual objects (109) or virtual depth (54). Other sensors, such as a gyroscope or accelerometer, can interface with the headset (103) to infer the user's movement and position.

[0129] Additional Vehicle Embodiments 16A-29C illustrate additional embodiments of display systems that can be mounted on a vehicle, i.e., configured to integrate into a vehicle. As this terminology is used in this disclosure, a display system is "configured" to be integrated into a vehicle if it is actually integrated into a vehicle or if it is specifically designed, configured, or adapted for integration into a vehicle. While the following description focuses primarily on automotive implementations for ease of explanation, it will be recognized that at least some of the techniques introduced in the following description can also be applied to other types of vehicles.

[0130] FIG. 16A shows the touch screen ( 52 2C shows an example implementation of a field-generating cavity (151) associated with a touchscreen (152). This implementation could be, for example, a vehicle center console display. A touchscreen (152) includes interactive buttons (153). Behind the touchscreen (152) is an FEC (Field Emission Control) consisting of a set of relay optics to guide the display content upward. Light corresponding to the display content is reflected by a mirror or semi-transparent reflector (3) and reaches the observer through an aperture (154). This semi-transparent reflector could be used to overlay the display content on the windshield as a see-through head-up display. The observer sees multiple virtual images (90) at multiple depths. The aperture could include an anti-reflective coating or polarizing film to reduce ambient light, or it could be a privacy film, or a combination of such layers to create a shielding layer (47, 48, or 49) (FIG. 2C).

[0131] Figure 16B shows a side view of the FEC implementation of Figure 16A. Light is emitted from two displays (1), which are segmented to display multiple depth images. For example, a pair of display elements split into three images can generate six virtual depths. Similarly, segmenting into four generates eight images, and so on. Each image is guided vertically by a pair of beam splitters (19). Light from the left display, behind the touchscreen (152), is guided directly upward. Light emitted from the right display is first directed downward, reflected by a mirror (3), and then guided upward. All light is reflected off the top of the device by a back reflector or back semi-transparent reflector (3) and reaches the viewer through an aperture (154).

[0132] Another exemplary embodiment is shown in Figure 16C. Here, all light travels coaxially. Light is emitted from the display (1) and passes through a QBQ (30). The resulting y-polarized light travels through the cavity and is reflected by the PBS (20). Any other reflective polarizer, such as a wire grid, could be used instead of the PBS. The light then travels in the opposite direction and is reflected by the QBQ (30), which rotates the polarization to produce x-polarized light. This light then passes through the PBS (20) and then through a polarization modulation layer (PML) (167). The PML could be an addressable liquid crystal matrix that functions to rotate the polarization angle of each pixel of the image by a programmable amount. The light then passes through the QWP (10), which converts the light into left- and right-handed circular polarization, such that the ratio of LCP to RCP in each pixel corresponds to the polarization angle of each pixel after the PML. The light then passes through a Pancharatnam-Berry (PB) phase element (168) to the viewer. The PB element can be a pre-structured or dynamically addressable liquid crystal layer, with each pixel element functioning as a HWP. If the PB element is programmed to be a lens, the LCP (RCP) light will be focused and the RCP (LCP) light will diverge, resulting in virtual images closer to and further from the viewer, respectively. The PB element could also be programmed as a grating that deflects the LCP light in one direction and the RCP light in a second direction.

[0133] In some embodiments, multiple PB elements can be combined into an Alvarez-type element. In such cases, the lateral displacement of a first PB element relative to a second element affects the optical function. Tuning this position can change the effect and depth of focus of the image.

[0134] The geometry of Figure 16B can be modified to produce the embodiments of Figures 17A-17E6, which show different configurations in which a touchscreen (152) is associated with two FECs, one on the left side of the touchscreen (152) and one on the right side of the touchscreen (152). The virtual images (90) can be far from the observer, as shown in Figure 17A, or they can be closer to the observer, as shown in Figure 17B. In some embodiments, the observer can interact with the depth layer through gestures recognized by the depth camera (155). Figure 17C shows such an embodiment from a frontal view. In these embodiments, each FEC (151) guides light to each aperture (154) so ​​that one set of virtual images is directed toward the observer, the driver, and one set of virtual images is directed toward the observer, the passenger.

[0135] One exemplary embodiment is shown in Figure 17D, which is a top view of an FEC behind a touchscreen (152). A first display behind the touchscreen (152) guides light through a set of relay beam splitters (19) to an aperture (154) on the left. A second display (1) guides light through a set of relay beam splitters (19) to an aperture (154) on the right.

[0136] This embodiment uses a phase conjugate element. In this disclosure, a "phase conjugate" optic is an optical element that reverses the lateral momentum of a wavefront. This could be a reflective element, such as a retroreflector, or a transmissive element, such as a retroreflector. This could be an active element and operate via a nonlinear optical effect, such as phase conjugation. Furthermore, the term "positive depth" corresponds to a virtual image depth that is farther from the observer than the display system. "Negative depth" corresponds to a virtual image depth that is closer to the observer than the physical display, such that the image appears to protrude from the aperture of the display system.

[0137] In Figure 17D, in front of both apertures, a retrorefractive element (158) can conjugate the lateral momentum of the light so that the resulting light converges and creates an image in front of the aperture (154) closer to the viewer, i.e., with negative depth. The viewer can then interact with these hovering depth images through gestures recognized by a depth camera (155) integrated into the aperture. In some embodiments, the lateral momentum of the light is conjugated by a retroreflector (159), as shown in Figure 17E. Light redirected to either side is linearly polarized as it passes through the PBS (20), passes through the QWP (10), and is then reflected by the retroreflector (159). Upon passing through the QWP a second time, the light is linearly polarized so that it is reflected by the PBS (20) to create a virtual image closer to the viewer than the display system. In some embodiments, the retrorefractive optics can comprise 1D-1D elements, lenticular arrays, or axially varying graded-index (GRIN) elements. In some embodiments, the touchscreen 152 itself can have a thin FEC incorporated into all or part of it, such that some segments of the screen appear to be recessed into or protrude from the screen. In some embodiments, the touchscreen 152, or portions thereof, can be covered with polarization-dependent metasurfaces or retroreflective microstructures to provide negative depth to a virtual menu bar.

[0138] Figures 18A-18C show an implementation with an extended aperture (154) whose area is larger than the touchscreen (152). In Figure 18A, the FEC (151) is placed behind the touchscreen (152) with interactive buttons (153) and generates downward-guided display content. The display content exits through the extended aperture (154). The extended aperture can generate both a near virtual image (90) with negative depth, as shown in Figure 18A, and a far virtual image (90) with positive depth, as shown in Figure 18B.

[0139] A side view of an exemplary FEC embodiment for this implementation is shown in Figure 18C. A first display (1) behind a touchscreen (152) emits light through a first beam splitter (19). Similarly, a second display (1) emits light through a second beam splitter (19). Both displays are segmented to accommodate multiple images. The beam splitters act as light guides that reflect the light downward. Both beam splitters have gradient reflectivities so that the intensity is uniform for light rays that are reflected a different number of times. At the bottom of the display system, the light is reflected by a tilted mirror (3), which in some embodiments can be a retroreflector, and passes through an aperture (154) to the viewer, generating multiple virtual images (90). In some embodiments, polarization-dependent elements could affect the number of round trips between the reflector and the aperture.

[0140] Figure 18D shows side and front views of an embodiment with an FEC (151) having an extended surface that exhibits two layer sets of virtual depth (90). The display system can include interactive buttons (153). In some embodiments, as shown in Figure 18E, the FEC can include an axially modulated refractive index gradient material (121) where the refractive index increases along the optical axis to gradually collimate the light. A reverse refractive element (158) then conjugates the lateral momentum so that the slightly diverging light becomes slightly converging light, creating a virtual image closer to the viewer.

[0141] In any of the embodiments or implementations disclosed in this disclosure, the virtual imagery can be synchronized with any of the vehicle's systems or user inputs, such as modulated by the sound system, controlled by Wi-Fi, observer assistance, GPS, acceleration, deceleration, vehicle rotation, door opening and closing, head and eye tracking, or gesture input, or electronic signals for vehicle operation.

[0142] As shown in FIG. 19A, a display system such as that disclosed herein can be implemented as (or part of) an instrument cluster behind a steering wheel (160). The FEC (151) has a prismatic or triangular structure to maintain a small form factor and generates a virtual image (90). FIG. 19B shows a side view of an exemplary embodiment of this prismatic structure. Y-polarized light is emitted upward from the first display (1) through a beam splitter (19). This light is then reflected by a tilted PBS (20) to a second beam splitter (19), where it is then reflected by the LC layers (12, 13), which rotate the light to x-polarized light, after which it passes through the PBS (20) and toward the viewer. Light from the second display (1) is emitted horizontally. Depending on the state of the LC layers (12, 13), the light becomes x-polarized and passes directly through the PBS (20) to the viewer without reflection. Alternatively, the light can be y-polarized. In this case, the light is first reflected by the PBS (20), then by the first beam splitter (19), then by the LC layers (12, 13) and rotated to x-polarization, and finally passes through the PBS (20) to the viewer. Thus, in this embodiment, there are three virtual depths within a small form factor. The LC trigger signal can be derived from content with embedded depth codes on the side of the image, or from the display driver hardware. In some embodiments, the video code is a periodic signal. As shown in Figure 19C, the FEC (151) behind the steering wheel (160) could have elements controlled by an electrical signal (26) from a piezoelectrically driven accelerometer, so that depth is affected by vehicle acceleration.

[0143] As shown in Figure 19C, the FEC 151 may be controlled in part by a control circuit 26 that relays acceleration information about the vehicle, which information may be displayed in a virtual image 90 in a convenient manner.

[0144] Figure 19D shows an FEC similar to that of Figures 18A-18B, except that the FEC is a display for generating a virtual image (90) of the instrument cluster behind the steering wheel (160). Figure 19E is a side view of the configuration of Figure 19D. Light is emitted from two displays (1) and guided along the displays by beam splitters or reflective coatings. The light is reflected by angled mirrors (3) and reaches the observer through apertures (154). The displays are segmented so that each can generate multiple virtual images. In this embodiment, the FEC can be hidden under the dashboard or extended behind the vehicle's firewall to provide more space for tuning the image depth or a wider range of possible image depths. Figure 19F shows an embodiment similar to Figure 19D, with part of the display system hidden under the dashboard and the same prismatic FEC as Figures 16A and 16D.

[0145] Figures 20A-20C show a further alternative embodiment. In Figure 20A, light is emitted by a tilted display (1) into a QWP (10), generating circularly polarized light. This display can be segmented to generate multiple virtual images and can have emission profiles to direct different light rays in different directions. The light then passes through a beam splitter (19). A portion of the circularly polarized light strikes the PBS (20), and a portion of that light exits the FEC as x-polarized light, creating a first depth. The reflected light is y-polarized and is reflected by the first beam splitter (19) downward to the second QWP (10), where it is reflected by the curved mirror (3) and back toward the second QWP. The light becomes x-polarized, reflects by the first beam splitter (19), and exits the cavity through the PBS (20), creating a second depth. Finally, the portion of the circularly polarized light that passed through the first beam splitter (19) travels straight down and is reflected by the curved mirror (3), before making a double pass through the second QWP. This light travels upward and is reflected by the first beam splitter (19), and the x-polarized portion of the light travels to the PBS (20), creating a third depth. A total of three depths are generated. Figure 20B shows a perspective view of the virtual image (90) generated by the FEC embodiment (151) from Figure 20A with the curved mirror (3) at the bottom. The image size can be larger than the physical display size.

[0146] The embodiment of Figure 20C maintains a low-profile form factor in a coaxial design by using a pair of micro-fabricated 1D-1D structures within the FEC. The 1D-1D structure configuration produces both positive and negative depths (90). The structures can be 1D macro-fabricated (local curvature periodicity greater than 1 cm) or 1D micro-fabricated (local curvature periodicity less than 1 cm) and can include polarization-influencing elements to alter round-trip times.

[0147] As shown in Figure 21A, an FEC can be implemented in a steering column (161) to generate a negative depth image (90) in front of the steering wheel (160) for driver-viewer interaction. Light is emitted by multiple displays (1) guided by reflective elements (3) around the inside surface of the steering column. The light exits through apertures (154) to a viewer who can interact with the depth layer via gesture sensors and / or depth cameras (155). Figure 21B shows a front perspective view of this embodiment. In some embodiments, the pipes could be replaced with parabolic or spherical mirrors facing each other. A hole exists in the center of each mirror so that the core display is centered on the back mirror, and aperture optics with a quarter-wave plate and polarizer are placed on the front mirror to cancel ambient light entering the display system.

[0148] FIG. 22A shows an overhead view of an application in which a scene (166) located outside a vehicle (162) is in the blind spot of the vehicle's driver (the observer in this situation). The scene is captured by a depth camera (155). The information is processed and projected as light by the FEC (151) through an angular profiling layer (11). This changes the light direction to a side window (164), which reflects the light toward the observer. The side window may also have an angular profiling layer (11) to help direct the light. The observer views a virtual image (90) through the side window, virtually extending the side mirror (115) to effectively reduce or eliminate the blind spot. The virtual image may also include text information such as warnings or object labels. Due to the curvature of the vehicle's reflective surfaces, the image content generated by the display system is pre-compensated to ensure the observer sees an undistorted image.

[0149] FIG. 22B shows a driver observer view diagram for the embodiment described in FIG. 22A. An aperture (154) is located immediately in front of the FEC, emitting light through an angular profiling layer (11) and redirecting it to the driver observer's side window. The side window could also be provided with an angular profiling layer (11) to assist in directing the light. The light is reflected from the side window and directed toward the driver observer (116). The content of the virtual image (90) comprises portions of the scene located in the observer's blind spot. The images are obtained with the side mirror (115) virtually augmented to show these images at their correct depth. Similarly, in FIG. 22C, a similar FEC emits light through the aperture and angular profiling layer to the passenger observer's side window, which then reflects the light back to the passenger observer (165). The virtual image (90) can include text messages or other information about the vehicle's status or the environment surrounding the side mirror (115).

[0150] Figure 22D shows an internal view of a vehicle (162) in an embodiment similar to that of Figure 22A. The display system is ultra-bright and displays interlaced images "A," "B," and "C" (171) in Figure 22E. Light is sent through an aperture (154) and then sent to an angular profiling layer (11). In some embodiments, the angular profiling layer interlaces angles to different adjacent pixels. Alternatively, the display system itself encodes light rays using an internal angular profiling layer (e.g., a lenticular array) to create highly directional light rays. With angular profiling, each light path for each image can travel in widely different directions, over tens of degrees, and be simultaneously reflected off multiple vehicle reflective surfaces, including the side windows or windshield (163). An observer (165) can view each image from each direction.

[0151] Figures 22F-22H show possible embodiments of the display system of Figures 22A-22D. In the overhead view of Figure 22F, light is emitted from the display (1) into an FEC (151) that modulates the optical depth. The light then passes through an aperture and an angular profiling layer (11), which redirects it to a side window (164). The side window, which may include another angular profiling layer (11), redirects the light to an observer (165), who may be the driver or passenger.

[0152] Figure 22G shows an overhead view of an alternative FEC embodiment. Light is emitted from the display (1) into a QBQ (30), which converts x-polarized light from the display to y-polarized light. The light is reflected by a cross-polarized PBS (20) (or alternatively, another type of polarizer or reflective polarizer) and makes a second pass through the cavity. Upon reflection from the QBQ, the light rotates back to x-polarized light and then passes through the PBS (20) and then through a PML (167). The PML (167) rotates the polarization angle of each pixel by a pre-calculated amount. The light then passes through a QWP (10), which converts the light into a linear combination of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) light. The ratio of LCP to RCP for each pixel is proportional to the polarization rotation angle by the PML. The light then passes through one or more PB elements (168), which deflect the RCP light in one direction and the LCP light in a different direction. The RCP or LCP light strikes both side windows (164), each of which may have an angular profiling layer (11). The light is then directed toward a single observer or multiple observers. An example of a PB element would be a stack of dimmable LC gratings, allowing for dynamic tuning of the angle. Multiple PB elements could be displaced relative to one another to create an Alvarez-type lens, allowing for tuning of the relative displacement to affect the light path.

[0153] Figure 22H shows a side view of an alternative embodiment of the application of Figure 22A. Light is emitted from two displays (1) and each passes through a PML (167) to modulate the polarization orientation of each pixel. The displays can be segmented to generate multiple virtual images. The light is guided along a horizontal light-guiding structure (similar to that in the embodiment of Figure 19E). The light is reflected upward by a mirror (3) to a QWP (10), which converts the polarization angle information into an LCP image and an RCP image. The upward-traveling light is reflected by a PB element (168), such as an LC grating, with the LCP light traveling toward the driver's side window (164) and the RCP light traveling toward the passenger's side window (164). Each window can include an additional angular profile layer (11) to help return the light to the viewer.

[0154] Figure 23 shows an application embodiment in which a vehicle (162) has a wide field of view depth camera (155) that captures a scene (166) facing the vehicle backward. The information is transmitted to an aperture display through an optical pipeline or waveguide (170). The light can be modulated by an FEC (151) that projects multiple virtual images at multiple depths (90) in front of the viewer.

[0155] Figures 24A-24C illustrate applications that effectively make portions of a vehicle transparent. Figure 24A shows a top view of an application in which a depth camera (155) captures a scene in front of an observer that is not directly visible. The information captured by the depth camera (155) is processed by an FEC (151) and projected through an aperture to the observer (165), generating a virtual image (90) of the hidden scene. In such applications, the display system resembles a mirror but does not require a window or other transparent panel, which could be useful in various aeronautical and defense applications.

[0156] FIG. 24B shows an observer's view of the application embodiment described in FIG. 24A, which is a video see-through virtual window. As the observer looks into the opening (154), they see a virtual image (90) whose depth corresponds to the location of different objects in the physical scene in front of the vehicle (162), effectively making the engine compartment see-through. This application allows the vehicle to navigate cluttered environments or tight spaces. FIG. 24C shows a side view of the application embodiment described in FIG. 24A. The observer (165) looks into the opening of the FEC (151) and sees the virtual image (90), whose information is recorded by the depth camera (155) and whose position corresponds to the physical scene not normally visible to the observer. In this application, the term vehicle refers to a vehicle in general, including an airplane. In some embodiments, the video see-through virtual window may be used in place of a passenger window or an airplane windshield.

[0157] FIG. 25 shows an application embodiment with a depth camera (155) capable of measuring the speed of traffic (166) ahead. The information is fed to a display system, and the FEC (151) generates a virtual image (90) that provides information about the relative speed of traffic. The display system could, for example, display faster traffic as brighter, closer, or larger. In some embodiments, a video see-through virtual window could also provide augmented information on the displayed data. The video see-through virtual window could be stereoscopic, monocular, or both. This allows the driver to pay more attention to road conditions. The camera could, for example, function using the Doppler effect, time-of-flight effects in the time domain, or time-of-flight effects in the frequency domain.

[0158] 26A illustrates an application embodiment in which a hyperspectral depth camera (155) captures a scene (166) in low-light conditions and a display system computationally projects multiple virtual images at multiple depths (90) to an observer (165) via an FEC (151) integrated into the vehicle's windshield. The hyperspectral depth camera (155) may include, for example, any one or more of radar, lidar, infrared, or acoustic.

[0159] In an alternative embodiment shown in Figure 26B, an observer (165) faces a conventional 2D display (1). Behind the 2D display is an FEC (151) that directs light upward to be reflected by a windshield (163) to the observer (165) who views a virtual image (90) through the windshield. Figure 26C shows a side view of a possible embodiment of the FEC (151). There are three display elements (1). The leftmost one corresponds to the display where the observer views the 2D content directly. The display adjacent to it emits light to the right, and a set of beam splitters (19) directs all these light rays upward toward the windshield (163). The rightmost display emits light to the left. This light is directed downward by the beam splitter and reflected by the lower curved mirror (3), which directs the light upward through the beam splitter, where it is reflected by the windshield. The windshield directs all light from the FEC toward the viewer. The bottom mirror is curved to correct distortions upon reflection by the windshield, including, for example, astigmatism. An aperture (154) blocks ambient light from entering the display system.

[0160] In all embodiments in which a virtual image is directed to a viewer by a reflective element having a front and rear surface, reflections can generate a secondary ghost image from the rear surface, as shown in Figure 27 (solid line). In this example, light is directed upward from the FEC (151) through the windshield (163) to the viewer (165). The FEC can have a front display surface (1) that displays a normal 2D image. In such embodiments, the display content generated by the FEC can pre-compensate for ghost images. This can be generated, for example, by pre-calculated non-constructive interference or moiré effects.

[0161] Figures 28A-28C show an embodiment in which a display system such as the one described above is used for entertainment purposes. This could occur in any type of vehicle, such as a limousine, airplane, taxi, or ride-sharing vehicle. In Figure 28A, the display system emits light upward toward a reflective surface (3) attached to the ceiling of the vehicle (162). The curvature of the reflector, or the direction of the light beams emitted from the display system, is designed to reach the observer occupants. The reflector can include a diffractive optical element, such as a Fresnel element, to direct the light beams. The display system can have a translucent element so that the observer can see the display content overlaid on a scene from the outside world. A side view of a vehicle (162) with a similar embodiment is shown in Figure 28B. In Figure 28B, the display (1), FEC (151), and reflective surface (3) are all fixed to the ceiling of the vehicle. Light can be guided between the reflective surfaces. The guiding mechanism can be created by a light pipe or diffractive waveguide to guide light to the observer (165). Yet another entertainment embodiment is shown in FIG. 28C. In a vehicle (162), a display system extends across the entire interior row for multiple observers (165) to enjoy a shared viewing experience. The display system can be fixed in a fixed position or mounted on an articulating or foldable arm for positioning. Alternatively, the windshield itself can be used as the final reflector of the extended display system for all front occupants, achieving a similar shared viewing experience.

[0162] In some embodiments, the FEC systems described above can be used in conjunction with high-power light sources, such as LED or halogen lamps, to provide highlights or light structures with negative or positive projecting segments. In some embodiments, as shown in Figures 29A-29C, on the exterior of a vehicle (162), a virtual image (90) of a backup light, front light, or side turn light next to the side mirror (115) appears to an outside observer as floating in front of the vehicle or hidden behind a physical light element.

[0163] Overview of Exemplary Embodiments Particular embodiments of the techniques introduced in this disclosure are summarized in the following numbered examples.

[0164] 1. A display system comprising a light source and an optical subsystem optically coupled to the light source and including a reflector and at least one semi-reflective optical component, the optical subsystem configured to guide light rays to simultaneously display multiple virtual images to an observer, the light of each virtual image having different optical depths by traveling different distances within the optical subsystem before exiting the optical subsystem on a path toward the observer's eye, and the display system configured to be incorporated into a vehicle.

[0165] 2. The display system of Example 1 configured to be integrated into a vehicle instrument cluster for use by a driver of the vehicle.

[0166] 3. The display system of Example 1 or Example 2, wherein the display system is installed or configured to be installed at a location within the vehicle for use by an occupant of the vehicle.

[0167] 4. The display system of any of Examples 1-3, wherein the display system has a viewable zone large enough to simultaneously encompass both eyes of each of a plurality of observers when the observers are seated separately.

[0168] 5. The display system of any of Examples 1-4 configured for use as a center console display.

[0169] 6. The display system of any of Examples 1-5, wherein the display system is configured for use as an instrument cluster.

[0170] 7. The display system of any of Examples 1-6, wherein the display system is configured to use an Alvarez lens system or a Pancharatnam Berry phase element to generate multiple depth layers.

[0171] 8. The display system of any of Examples 1-7, wherein the display and optical subsystem elements are stacked on top of each other and mounted to the ceiling of the vehicle.

[0172] 9. The display system of any of Examples 1-8, further comprising an aperture for controlling how ambient light interacts with the display system.

[0173] 10. The display system of any of Examples 1-9, wherein the reflector and semi-reflective optics are configured to generate a virtual image having a horizontal size that is larger than a horizontal size of the physical display system.

[0174] 11. The display system of any of Examples 1-10, wherein the light source is a segmented display, the display system is configured to present multiple images projected to a viewer at multiple depths, and further comprises multiple semi-reflective optical elements for guiding light generated by the display through an extended aperture.

[0175] 12. A display system described in any of Examples 1 to 11, wherein at least one element of the display system is segmented to provide different virtual images to each of the observer's left and right eyes to generate stereoscopic and monocular depth cues.

[0176] 13. The display system of any of Examples 1-12, wherein the optical subsystem comprises at least one polarization-influencing element such that light of a first polarization forms a first virtual image and light of a second polarization forms a second virtual image.

[0177] 14. The display system of any of Examples 1-13, wherein the light source is a display panel having a display surface, and the multiple virtual depths are at apparent distances from the observer that are different from the depth of the observer, and the multiple virtual depths are at apparent distances from the observer that are different from the depth of the display surface from the observer.

[0178] 15. The display system of any of Examples 1-14, further comprising sensors and control circuitry for enabling a viewer to interact with the virtual image at different depths using mid-air gesture control.

[0179] 16. The display system of any of Examples 1-15, further comprising sensors and control circuitry for enabling a viewer to interact with the virtual image at different depths using the touch screen.

[0180] 17. The display system of any of Examples 1 to 16, wherein the light source is a display and further comprising a phase conjugate element, the phase conjugate element forming the virtual image at a closer depth, wherein the phase conjugate element forms the virtual image at a depth closer to the observer than the distance between the display and the screen.

[0181] 18. The display system of any of Examples 1-17, wherein the optical subsystem comprises a plurality of 1D microformed or 1D macroformed elements, a first element of the plurality of elements having optical focusing power, and a second element of the plurality of elements having optical focusing power in a second dimension that is not parallel to the first dimension.

[0182] 19. A display system according to any of Examples 1 to 18, wherein the display system is positioned or configured to be positioned within a steering column of the vehicle such that when the display system is operating, the light is guided by the semi-reflective optical element and reflector along the inside of the steering column to an observer.

[0183] 20. The display device of any of Examples 1-19, further comprising a depth modulation element controlled by an accelerometer, wherein the display system is configured such that acceleration of the vehicle affects the virtual image.

[0184] 21. The display system of any of Examples 1-20, wherein at least a portion of the display system extends below the dashboard of the vehicle.

[0185] 22. The display system of Example 1, wherein the display system is coupled with a high-power light source and configured to generate structured headlights, taillights, or turn signal lights that appear to an observer outside the vehicle to be hovering away from or embedded within the vehicle.

[0186] 23. The display system of any of Examples 1 to 21 mounted on an exercise arm for use as a personal in-car entertainment system.

[0187] 24. A display system for use in a vehicle comprising: a light source; an optical subsystem optically coupled to the light source and including a reflector and at least one semi-reflective optical component, wherein the optical subsystem is configured to direct light rays such that light for each of a plurality of virtual images travels a different distance within the optical subsystem on a path toward an eye of an observer before exiting the optical subsystem, thereby providing a plurality of virtual images simultaneously viewed by the observer at a plurality of different optical depths, and the optical subsystem includes an angular profiling layer for directing light onto a reflective surface or a semi-reflective surface inside the vehicle for directing the virtual images to the observer, wherein display content displayed by the display system is pre-compensated by a combination of pre-compensation and the curvature of the reflective or semi-reflective surface inside the vehicle to produce a distortion-free virtual image for the observer.

[0188] 25. The display system of example 24, wherein the pre-compensated display content compensates for artifactual reflections from reflective surfaces inside the vehicle.

[0189] 26. The display system of example 24 or example 25, wherein the angular profiling layer is polarization dependent.

[0190] 27. A display system as claimed in any one of claims 24 to 26, wherein the optical subsystem comprises at least one polarization-influencing element that causes a first polarization of light to form a first virtual image at a first depth and causes a second polarization of light to form a second virtual image at a second depth.

[0191] 28. The display system of any of Examples 24-27, further comprising sensors and control circuitry for enabling a viewer to interact with the virtual image at different depths using mid-air gesture control.

[0192] 29. A visualization system for use in a vehicle, comprising: a light source; a camera that acquires information about a scene external to the vehicle; an optical subsystem optically coupled to the light source and including a reflector and at least one semi-reflective optical component, the optical subsystem configured to direct light rays to provide a plurality of virtual images that appear to the observer simultaneously at a plurality of different optical depths by causing each light of a plurality of virtual images to travel a different distance within the optical subsystem on a path toward the observer's eye before exiting the optical subsystem, one or more virtual images representing or including information about the scene external to the vehicle based on information acquired by the camera; and a processor circuitry that processes information about the depth and angle of the scene used by the optical subsystem to display the scene.

[0193] 30. The visualization system of example 29, further comprising an aperture for controlling ambient light incident on the display system.

[0194] 31. The visualization system of Example 29 or Example 30, further comprising an angular profiling layer for redirecting information acquired by one or more depth cameras positioned around the exterior of the vehicle to an interior portion of the side window.

[0195] 32. A visualization system described in any of Examples 29 to 31, wherein an image of a scene in front of the vehicle that is hidden from the observer and acquired by the camera is projected to the observer such that the virtual image position of the image of the scene corresponds to the physical position of the scene.

[0196] 33. A visualization system described in any of Examples 29 to 32, wherein the display content generated by the display system is interlaced with multiple images, and the optical subsystem redirects each of the multiple images to multiple reflective surfaces inside the vehicle.

[0197] 34. A visualization system according to any of Examples 29 to 33, wherein the camera is configured to sense the speed of surrounding traffic, and the display system is configured to project information about the speed of the surrounding traffic to alert an observer.

[0198] 35. A visualization system according to any of Examples 29-34, wherein the camera is configured to sense the speed of surrounding traffic and the display system is configured to project information about the speed of surrounding traffic to alert the observer.

[0199] 36. A visualization system described in any of Examples 29 to 35, wherein the optical subsystem comprises a plurality of 1D microformed or 1D macroformed elements such that a first element of the plurality of elements has optical focusing power in a first dimension and a second element of the plurality of elements has optical focusing power in a second dimension that is not parallel to the first dimension.

Claims

1. 1. A display system comprising: a first display that emits light rays in a first direction; a second display that emits light rays in a second direction; and an optical subsystem; the optical subsystem: a first semi-reflective optical component optically coupled to the first display and the second display and including a second semi-reflective optical component; a surface of the first semi-reflective optical component that receives light from the first display is positioned on a display surface of the first display; and the optical subsystem is configured to direct light rays to provide a plurality of virtual images simultaneously seen by an observer at a plurality of different optical depths by causing the light rays propagating in the first direction to travel a different distance within the optical subsystem than the light rays propagating in the second direction before exiting the optical subsystem on a path towards the observer's eye, such that the light rays propagating in the first direction are incident on the first semi-reflective optical component and then on the second semi-reflective optical component, and the light rays propagating in the second direction are incident on the second semi-reflective optical component and then on the first semi-reflective optical component, the optical subsystem further includes a shielding layer formed as a single subassembly, the shielding layer including an anti-reflection (AR) coating and an absorptive polarizer (AP) on one side of the shielding layer facing the viewer; The display system is configured to be integrated into a vehicle. Display system.

2. The display system of claim 1 , wherein the display system is configured to be integrated into an instrument cluster of the vehicle for use by a driver of the vehicle.

3. 10. The display system of claim 1, wherein the display system is mounted or configured to be mounted at a location within the vehicle for use by an occupant of the vehicle.

4. 10. The display system of claim 1, wherein the display system has a viewable zone large enough to simultaneously encompass both eyes of each of a plurality of observers when each observer is seated in a different seating position in the vehicle.

5. The display system of claim 1 , wherein the display system is configured for use as a center console display.

6. The display system of claim 1 , wherein the display system is configured for use as an instrument cluster.

7. The display system of claim 1 , wherein the display system is configured to create multiple depth layers using an Alvarez lens system or a Pancharatnam Berry phase element.

8. 10. The display system of claim 1, wherein the display system and the optical subsystem elements are stacked together and mounted to the ceiling of the vehicle.

9. 10. The display system of claim 1, further comprising an aperture for controlling how ambient light interacts with the display system.

10. The display system of claim 1 , wherein the optical subsystem is configured to generate a virtual image having a horizontal size that is larger than a horizontal size of the physical display system.

11. 10. The display system of claim 1, wherein the light source is a segmented display, the display system is configured to present a plurality of images projected at multiple depths to an observer, and further comprises a plurality of semi-reflective optical components that guide the light generated by the display through an extended aperture.

12. 10. The display system of claim 1, wherein at least one element of the display system is segmented to provide different virtual images to each of the left and right eyes of an observer to generate stereoscopic and monocular depth cues.

13. 10. The display system of claim 1, wherein the optical subsystem comprises at least one polarization-influencing element such that a first polarization of light forms a first virtual image and a second polarization of light forms a second virtual image.

14. 10. The display system of claim 1, wherein the light source is a display panel having a display surface, and wherein a plurality of virtual depths are at apparent distances from the observer that are different from the depth of the display surface from the observer.

15. The display system of claim 1 , further comprising sensors and control circuitry that enable the viewer to interact with virtual images at different depths using air gesture control.

16. 10. The display system of claim 1, further comprising sensors and control circuitry that enable the observer to interact with virtual images at different depths using a touch screen.

17. 2. The display system of claim 1, wherein the light source is a display, and the display system further comprises a phase conjugate element, the phase conjugate element forming a virtual image at a depth closer to the observer than the distance between the display and the observer.

18. 2. The display system of claim 1, wherein the optical subsystem comprises a plurality of 1D microformed or 1D macroformed elements, a first element of the plurality of elements having optical focusing power in a first dimension, and a second element of the plurality of elements having optical focusing power in a second dimension that is not parallel to the first dimension.

19. 10. The display system of claim 1, wherein the display system is positioned or configured to be positioned within the steering column such that when the display system is operating, the light is guided by the optical subsystem along the inside of the steering column to an observer.

20. 10. The display system of claim 1, further comprising an accelerometer-controlled depth-modulating element, the display system configured such that acceleration of the vehicle affects the virtual image.

21. The display system of claim 1 , wherein at least a portion of the display system extends below a dashboard of the vehicle.

22. 10. The display system of claim 1, wherein the display system is coupled to a high-power light source and configured to generate structured headlights, taillights, or turn signals that appear to an observer outside the vehicle to be hovering away from the vehicle or embedded in the vehicle.

23. 10. The display system of claim 1, wherein the display system is mounted on an exercise arm for use as a personal in-car entertainment system.

24. 1. A display system for use in a vehicle, comprising: A light source and an optical subsystem optically coupled to the light source and including a reflector and at least one semi-reflective optical component, the optical subsystem configured to direct light rays to provide a plurality of virtual images simultaneously seen by the observer at a plurality of different optical depths by causing light for each of the plurality of virtual images to travel a different distance within the optical subsystem on a path toward the observer's eye before exiting the optical subsystem, the plurality of virtual images each appearing at a plurality of different optical depths; and an optical subsystem including a directional film external to the optical subsystem that directs light onto a reflective or semi-reflective surface inside the vehicle to direct the virtual images to the observer. Equipped with the display content displayed by the display system is pre-compensated to produce a distortion-free virtual image for the observer by a combination of pre-compensation and curvature of reflective or semi-reflective surfaces within the vehicle; Display system.

25. 25. The display system of claim 24, wherein the pre-compensated display content compensates for artifactual reflections from the interior reflective surfaces of the vehicle.

26. 25. The display system of claim 24, wherein the directional film is polarization dependent.

27. 25. The display system of claim 24, wherein the optical subsystem comprises at least one polarization-influencing element that causes a first virtual image to be formed at a first depth with a first polarization of light and a second virtual image to be formed at a second depth with a second polarization of light.

28. 25. The display system of claim 24, further comprising sensors and control circuitry that enables the viewer to interact with virtual images at different depths using air gesture control.

29. 1. A visualization system for use in a vehicle, comprising: a first display that emits light rays in a first direction and a second display that emits light rays in a second direction; a camera for acquiring information about a scene external to the vehicle; an optical subsystem optically coupled to the first display and the second display and including a first semi-reflective optical component and a second semi-reflective optical component, a surface of the first semi-reflective optical component that receives light from the first display is positioned on a display surface of the first display; and the optical subsystem is configured to direct light rays to provide a plurality of virtual images simultaneously seen by an observer, each appearing at a plurality of different optical depths, by causing light rays propagating in the first direction to travel a different distance within the optical subsystem than light rays propagating in the second direction before exiting the optical subsystem on a path toward an eye of the observer, such that light rays propagating in the first direction are incident on the first semi-reflective optical element and then on the second semi-reflective optical element, and light rays propagating in the second direction are sequentially incident on the second semi-reflective optical element and then on the first semi-reflective optical element, the optical subsystem further includes a shielding layer formed as a single subassembly, the shielding layer including an anti-reflection (AR) coating and an absorptive polarizer (AP) on one side of the shielding layer facing the viewer. an optical subsystem; a processor circuit for processing depth and angle information about the scene used by the optical subsystem to display the scene; A visualization system comprising:

30. 30. The visualization system of claim 29, further comprising an aperture for controlling ambient light entering the visualization system.

31. 30. The visualization system of claim 29, further comprising an angular profiling layer for redirecting information acquired by one or more depth cameras positioned around the exterior of the vehicle to an interior portion of a side window of the vehicle so that the observer virtually extends the image produced by the side mirror of the vehicle.

32. 30. The visualization system of claim 29, wherein an image of a scene in front of the vehicle that is hidden from the observer and acquired by the camera is projected to the observer such that a virtual image position of the image of the scene corresponds to a physical position of the scene.

33. 30. The visualization system of claim 29, wherein the display content generated by the visualization system is interlaced with a plurality of images, and wherein the optical subsystem redirects each of the plurality of images to a plurality of reflective surfaces within the vehicle.

34. 30. The visualization system of claim 29, wherein the camera is configured to sense a speed of surrounding traffic, and the visualization system is configured to project information about the speed of surrounding traffic to alert the observer.

35. 30. The visualization system of claim 29, wherein the camera is configured to sense electromagnetic radiation that is invisible to humans, and the visualization system is configured to display information about the sensed electromagnetic radiation to an observer to enhance visibility of an environment surrounding the vehicle.

36. 30. The visualization system of claim 29, wherein the optical subsystem comprises a plurality of 1D microformed or 1D macroformed elements such that a first element of the plurality of elements has optical focusing power in a first dimension and a second element of the plurality of elements has optical focusing power in a second dimension that is not parallel to the first dimension.

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