Fresnel Lens Coated By Reflective Polarizers

Abstract

An example apparatus may include a display and an optical configuration configured to provide an image of the display, for example in a head-mounted device. The optical construction may include a Fresnel lens assembly that includes a Fresnel lens and a reflective polarizer. The Fresnel lens may have a structured surface that includes a plurality of tangent planes, and may have a step between pairs of adjacent tangent planes. The reflective polarizer may include a plurality of reflective polarizer portions, where each reflective polarizer portion conforms to a corresponding tangent plane of the Fresnel lens. The reflective polarizer may be configured to reflect the first polarized incident light and transmit the second polarized incident light. When a user wears the device, the optical configuration may form an image of the display viewable by the user. Other apparatus, methods, systems, and computer readable media are also disclosed.

Description

Technical Field

[0001] The present disclosure relates generally to optical constructions, devices including optical constructions, and associated methods or apparatus. Background Art

[0002] Lenses and other optical components are ubiquitous in both consumer and commercial products, such as cameras, displays, and sensors. Fresnel lenses were originally deployed in lighthouses to increase the distance at which ships can see the light from the lighthouse. Using Fresnel lenses can be advantageous because they can be thinner (and often lighter) than traditional lenses of similar optical power. However, the design and manufacture of Fresnel lenses involves many design trade-offs. Summary of the invention

[0003] According to a first aspect of the present disclosure, there is provided a device including a Fresnel lens assembly, wherein the Fresnel lens assembly includes: a Fresnel lens; and a reflective polarizer, wherein the Fresnel lens has a structured surface, the structured surface includes a plurality of facets; the reflective polarizer includes a plurality of reflective polarizer portions; each of the plurality of reflective polarizer portions conforms to a corresponding facet among the plurality of facets; the reflective polarizer is configured to reflect light of a first polarization incident on the reflective polarizer; and the reflective polarizer is configured to transmit light of a second polarization incident on the reflective polarizer.

[0004] In some embodiments, the first polarization can be circularly polarized light of a first handedness; the second polarization is circularly polarized light of a second handedness; and the reflective polarizer includes a chiral solid.

[0005] In some embodiments, the first polarization may be linearly polarized light in a first direction; the second polarization may be linearly polarized light in a second direction; and the first direction is orthogonal to the second direction.

[0006] In some embodiments, the reflective polarizer may include an optical multilayer film.

[0007] In some embodiments, the plurality of facets may include a central facet; and the reflective polarizer includes a central portion that conforms to the central facet.

[0008] In some embodiments, the plurality of facets may further include an annular facet; the reflective polarizer includes an annular portion conforming to the annular facet; the central facet is a circular facet; and the annular facet surrounds the central facet and is concentric with the central facet.

[0009] In some embodiments, the structured surface of the Fresnel lens may include steps between adjacent facets among the plurality of facets; and the reflective polarizer does not cover the steps of the structured surface.

[0010] In some embodiments, each reflective polarizer segment in the plurality of reflective polarizer segments can be attached to the corresponding facet in the plurality of facets using an adhesive layer.

[0011] In some embodiments, each reflective polarizer portion of the plurality of reflective polarizer portions can be sized to match the corresponding facet of the plurality of facets.

[0012] In some embodiments, the Fresnel lens assembly may further include a filled polymer layer disposed above the reflective polarizer; and the filled polymer layer includes an optically transparent polymer.

[0013] In some embodiments, the reflective polarizer can include a first surface that conforms to the structured surface of the Fresnel lens and a second surface that includes external facets and external steps.

[0014] In some embodiments, the device may also include: a display; and an optical structure configured to provide an image of the display, wherein: the optical structure includes the Fresnel lens assembly; the device includes a head-mounted device; and when a user of the device wears the head-mounted device, the user is able to see the image of the display.

[0015] In some embodiments, the apparatus may include an augmented reality device or a virtual reality device.

[0016] In some embodiments, the optical construction may include a folded optical configuration; and when light from the display passes from the display through the optical construction to form the image of the display at the user's eye, the light is reflected by and transmitted through the Fresnel lens assembly.

[0017] In some embodiments, the optical configuration may also include a beam splitter lens and an optical delay.

[0018] In some embodiments, the display can be configured to emit light having circular polarization.

[0019] According to another aspect of the present disclosure, a method is provided, the method comprising: forming a reflective polarizer on a substrate; patterning the reflective polarizer to form a reflective polarizer portion, the size of the reflective polarizer portion being set to match the corresponding cut surface of the Fresnel lens; and applying the reflective polarizer portion to the corresponding cut surface of the Fresnel lens by pushing the reflective polarizer portion against the corresponding cut surface of the Fresnel lens using a force applied to the substrate.

[0020] In some embodiments, the method may further include forming a fill layer conforming to the reflective polarizer portion, wherein: the fill layer comprises an optically transparent polymer.

[0021] In some embodiments, forming the reflective polarizer on the substrate may include forming the reflective polarizer on an elastomeric element.

[0022] In some embodiments, the method may further include removing the substrate so that the reflective polarizer portion remains bonded to a corresponding portion of the Fresnel lens, wherein: the reflective polarizer is adhered to the substrate with a UV reversible adhesive or a thermal reversible adhesive; and removing the substrate includes UV irradiation or thermal debonding.

[0023] It will be understood that any feature described herein as being suitable for incorporation into one or more aspects or embodiments of the present disclosure is intended to be applicable to any and all aspects and embodiments of the present disclosure. Other aspects of the present disclosure may be understood by those skilled in the art based on the specification, claims and drawings of the present disclosure. The foregoing general description and the following detailed description are exemplary and illustrative only, and are not limitations of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings illustrate many exemplary embodiments and are a part of the specification. Together with the following description, these drawings demonstrate and explain various principles of the present disclosure.

[0025] Figure 1 Example optical configurations of devices according to various embodiments are shown.

[0026] FIG. 2A to FIG. 2C Fresnel lens assemblies according to various embodiments are shown.

[0027] Figure 3 Light propagation through a cross section of an example Fresnel lens assembly is shown in accordance with various embodiments.

[0028] Figure 4 A cross section of an example Fresnel lens assembly is shown in accordance with various embodiments.

[0029] Figure 5 and Figure 6 A cross section of another example Fresnel lens assembly is shown in accordance with various embodiments.

[0030] FIG. 7A to FIG. 7D Attachment of a reflective polarizer to one or more facets of a Fresnel lens is shown according to various embodiments.

[0031] FIG. 8A to FIG. 8C A portion of a manufacturing apparatus that may be used to manufacture a Fresnel lens assembly according to various embodiments is shown.

[0032] Fig. 9 A Fresnel lens comprising linear facets separated by steps is shown according to various embodiments.

[0033] Fig.10 A Fresnel lens assembly is shown including a filler layer 1020 that flattens the faceted surface, according to various embodiments.

[0034] Fig.11 A Fresnel lens having a curved faceted surface is shown in accordance with various embodiments.

[0035] Fig.12 Fresnel lens assemblies having faceted Fresnel surfaces and curved surfaces are shown according to various embodiments.

[0036] Fig.13 A device including a display and an optical construction including a Fresnel lens assembly is shown according to various embodiments.

[0037] Fig.14 Reflective polarizer layers having both an inner faceted surface profile and an outer faceted surface profile are shown according to various embodiments.

[0038] Fig.15 Optical configurations according to various embodiments are shown.

[0039] Fig.16 Optical configurations and possible ray trajectories according to various embodiments are shown.

[0040] Figures 17 to 19 An example method of manufacturing a Fresnel lens assembly according to various embodiments is shown.

[0041] Fig. 20 Example methods of operating a Fresnel lens assembly according to various embodiments are shown.

[0042] Fig.21 is an illustration of exemplary augmented reality glasses that may be used in conjunction with embodiments of the present disclosure.

[0043] Fig. 22is an illustration of an exemplary virtual reality head-mounted viewer (headset) that can be used in conjunction with embodiments of the present disclosure.

[0044] In all drawings, the same reference numerals and descriptions represent similar but not necessarily identical elements. Although the exemplary embodiments described herein allow for various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and described in detail herein. However, the examples described herein are not intended to be limited to the specific forms disclosed. Instead, the present disclosure encompasses all modifications, equivalents, and alternatives that fall within the scope of the appended claims. DETAILED DESCRIPTION

[0045] The present disclosure generally relates to optical configurations, devices including optical configurations, and associated methods or apparatus. As explained in more detail below, embodiments of the present disclosure may include a Fresnel lens assembly suitable for a virtual reality system and / or an augmented reality system. The Fresnel lens assembly may include a reflective polarizer and a Fresnel lens.

[0046] The example apparatus may include an optical configuration including a Fresnel lens assembly. The example Fresnel lens assembly may include a reflective polarizer, for example, configured to reflect light of a first polarization and transmit light of a second polarization. For example, the reflective polarizer may reflect circularly polarized light of one handedness and transmit circularly polarized light of another handedness. The example apparatus may include a beam splitter lens, or in some examples, the example apparatus includes a second Fresnel lens assembly. The beam splitter lens may include a beam splitter formed as a coating on a lens.

[0047] Example reflective polarizers include, but are not limited to, cholesteric reflective polarizers (CLCs) and / or multilayer birefringent reflective polarizers. Other examples are discussed below.

[0048] Examples include apparatus including a folded optical construction, such as an apparatus including a Fresnel lens assembly. Use of a Fresnel lens assembly can allow for improved optical efficiency of the optical construction, such as by reducing losses associated with a beam splitter. Improved optical efficiency can provide one or more of the following: improved image appearance (e.g., improved image brightness, uniformity, and / or resolution), improved lens efficiency, reduced power consumption, and / or reduced heat generation for a given brightness. Examples also include associated methods, such as methods of making improved Fresnel lens assemblies, methods of making devices including one or more Fresnel lens assemblies, or methods of device use.

[0049] An example device may include a Fresnel lens assembly including a polarized reflector configured to reflect a first light polarization and transmit a second light polarization. In some examples, the Fresnel lens assembly may include a Fresnel lens having at least one faceted surface and a reflective polarizer. The reflective polarizer may include a layer located on one or more of the Fresnel facets. At least one surface of the Fresnel lens may include a plurality of facets, wherein adjacent facets are separated by steps (sometimes referred to as risers). The reflective polarizer may include a layer disposed adjacent to the Fresnel lens (e.g., the layer is supported by the facets). The reflective polarizer may conform to at least a portion of at least one of the facets. The example Fresnel lens may include an optical material, such as glass or an optical polymer. The example Fresnel lens may be substantially transparent to some visible wavelengths or all visible wavelengths.

[0050] In some examples, all portions of a reflective polarizer (e.g., supported by a facet of a Fresnel lens) can have similar construction and / or optical properties. In some examples, a Fresnel lens assembly can include reflective polarizer portions having different refractive index values ​​and / or optical dispersion properties. For example, different reflective polarizer portions can include different polymers. The optical properties of the reflective polarizer portions can be configured to improve the wavelength independence of the properties of the Fresnel lens assembly. In some examples, a Fresnel lens assembly can be configured as an achromatic lens using a suitably constructed reflective polarizer portion.

[0051] References below Figures 1 to 22 A detailed description of example embodiments is provided. Figure 1 An example optical configuration is shown. Figure 6 Example Fresnel lens assemblies, display systems, and imaging systems are shown, along with example light ray paths. 7A to 8C An example device manufacturing apparatus is shown. Figures 9 to 12 Other example Fresnel lenses and Fresnel lens assemblies that include reflective polarizers are shown. Figures 13 to 16 Other example Fresnel lens assemblies and optical configurations are shown. Figures 17 to 20 Example methods of device fabrication and operation are shown. Figure 21 to Figure 22 Example augmented reality systems and virtual reality systems are shown.

[0052] In some examples, the Fresnel lens can have a reflective polarizer formed as a layer on at least one of the Fresnel lens facets. The layer can include a multilayer optical film, a cholesteric liquid crystal, or an arrangement of anisotropic conductors (such as a nanowire arrangement). The facets and cladding layers can be embedded in a filling layer, which can include an optically transparent polymer. In some examples, the filling layer can flatten or otherwise smooth the outer surface of the Fresnel lens assembly. The refractive index and optical dispersion of the Fresnel lens material and the filling polymer can be configured to reduce chromatic aberration (e.g., reduce visually discernible color fringes in an image of a display). In some examples, the filling polymer can be configured as a second Fresnel lens, a geometric lens, and / or a diffractive lens. For example, the filled polymer may have a first surface having a facet that forms an interface with the first Fresnel lens and a second surface, such as a non-faceted surface (e.g., a planar surface or a curved surface, such as a concave surface, a convex surface, an aspheric surface, or a free surface) or a faceted surface. In some examples, the filled polymer may form a diffractive lens including a diffractive element on one or both surfaces. In some examples, a reflector or a reflective polarizer may be located between the facet of the first Fresnel lens and the filled polymer.

[0053] The optical material can be selected to provide low birefringence (e.g., optical retardation of less than one quarter wavelength (such as less than about λ / 10, for example, less than about λ / 20)). In some examples, the Fresnel lens and / or filling polymer (and / or other optical elements) can include a silicone polymer (such as polydimethylsiloxane (PDMS)), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyacrylate, polyurethane, polycarbonate, or other polymers. For example, a silicone polymer (e.g., PDMS) Fresnel lens can be supported on a rigid substrate, such as glass or a polymer (e.g., a relatively rigid polymer compared to the silicone polymer).

[0054] Vapor deposition of the coating may result in unwanted deposition on steps (sometimes called facets) between facets. Deposition on steps may be difficult to control and may result in visually discernible visible defects. A suitably patterned reflective polarizer portion may be selectively located on the facets of the Fresnel lens. In some examples, the reflective polarizer portion may be supported on an elastomeric element.

[0055] A Fresnel lens assembly including a reflective polarizer can be used in an augmented reality and / or virtual reality (AR / VR) system. In some examples, the Fresnel lens assembly can include a Fresnel lens and at least one other optical component, such as one or more of the following: a reflective polarizer, a filter, an absorptive polarizer, a diffractive element, an additional refractive element, a reflector, an anti-reflective film, a mechanical protective film (e.g., an anti-scratch film), or other optical components. A device including a Fresnel lens assembly can also include a display and a beam splitter.

[0056] In some examples, an AR / VR system may include a Fresnel lens assembly that includes a Fresnel lens and a polarizing reflector. The optical properties of the Fresnel lens may be optimized individually, but in some examples, the properties of the reflective polarizer, filler layer, or other layer may be configured to improve the performance of the Fresnel lens (e.g., by reducing chromatic aberration). In some examples, the Fresnel lens may be concave, convex, or may have a complex optical profile, such as a freeform surface. For example, the structured surface of the Fresnel lens may include multiple facets corresponding to multiple portions of the optical surface of the freeform lens, or multiple facets corresponding to multiple portions of other lens surfaces such as other concave surfaces or convex surfaces.

[0057] The wavelength-dependent properties of a Fresnel lens assembly or polarizing reflector can be adjusted by, for example, adjusting one or more parameters of a multilayer film construction (e.g., single layer refractive index, optical dispersion, and / or layer thickness). In some examples, a reflective polarizer can have a specific operating bandwidth, and the operating bandwidth can be adjusted using one or more parameters of one or more components (e.g., refractive index, optical dispersion, layer thickness, etc.).

[0058] Applications of Fresnel lens assemblies may include use in an optical construction of a wearable device (e.g., a head-mounted device), for example, using one or more Fresnel lens assemblies in an optical construction that is configured to form an image of a display that can be viewed by a user when the user wears the wearable device. Other example applications may include infrared (IR) suppression in, for example, imaging systems, display systems, transmission systems, or photovoltaic systems. Applications may include wavelength selection of optical waveguides, for example, using a Fresnel lens assembly at a waveguide input to select red wavelengths, green wavelengths, yellow wavelengths, and / or blue wavelengths for transmission along the waveguide. In some examples, the structured surface can be formed at the light entrance of any suitable optical component and configured as a Fresnel lens assembly.

[0059] Figure 1An optical structure 100 is shown, which includes a display 105, a beam splitter 120, a lens 130, and a polarizing reflector 140. A light beam emitted by the display is shown as a dotted line. Light 145 is emitted by the display portion 110 of the display 105, passes through the beam splitter 120 and the lens 130, and is reflected back from the polarizing reflector 140 as light 150. For ease of illustration, refraction at the lens surface is not shown. Light 150 is then reflected by the beam splitter to provide light 155, which passes through the polarizing reflector and is directed toward the user's eye as light 160. Stray beams such as beam 152 may reduce the intensity of the beam reaching the user's eye. The user's eye is not shown, but the viewing position (such as an eyebox) can be located on the right side of the optical structure, as shown. In some examples, the beam splitter 120 can be formed as a partially reflective film (e.g., a thin metal film) on the convex lens surface 125 of the lens 130. In some examples, the optical construction can also include an optical retarder, which can be included, for example, as a layer formed on surface 135 of polarizing reflector 140 .

[0060] Improvements in optical configuration 100 may be desired (such as reduced weight and power consumption in device applications). In some examples, lens 130 may be a Fresnel lens. In some examples, the polarizing reflector may be part of a Fresnel lens assembly. In some examples, a polarizing reflector may be used in place of a beam splitter to reduce losses associated with the beam splitter.

[0061] Fresnel lenses can effectively convert the curved surface of a refracting lens (for example, Figure 1 The Fresnel lens is shown as a convex lens surface 125 in FIG. 1 . The facets may include curved portions (or planar approximations thereof) that approximate corresponding portions of the convex surface. There may be steps between the facets, making the thickness of the Fresnel lens significantly less than that of a conventional convex lens. The Fresnel lens will be discussed in more detail below.

[0062] Figure 2A A Fresnel lens assembly 200 is shown that includes a Fresnel lens 210 and a reflective polarizer 220. In this example, a cut facet of the Fresnel lens 210 is clad by the reflective polarizer 220. The Fresnel lens assembly can be used as a reflective polarizing Fresnel lens.

[0063] Figure 2B A cross-sectional view of a Fresnel lens assembly 200 including a Fresnel lens 210 is shown. The facets of the Fresnel lens 210 support the layers that form the reflective polarizer 220. In this example, a filler layer 230 is used to flatten the faceted side of the Fresnel lens. The filler layer may include an optically transparent material such as glass or an optical polymer. The filler layer may include air, liquid, polymer, glass, ceramic, or a combination thereof.

[0064] In some examples, the filling layer may include one or more polymers, such as polyethylene, cyclic polyolefin (COP), acrylate polymers (e.g., polymethyl methacrylate PMMA), silicone polymers (e.g., polydimethylsiloxane PDMS), urethane polymers, polycarbonate, polyethylene, polyethylene naphthalate, polyethylene terephthalate, polystyrene, etc., and / or combinations, derivatives, or mixtures thereof. In some examples, the example filling layer may include a gel or a low modulus polymer (such as a low molecular weight PDMS or an oligomer (such as silicone oil)). In some examples, a portion (e.g., one or more layers of another optical element (such as a reflective polarizer)) may include one or more polymers (such as the polymers mentioned herein).

[0065] Figure 2C An optical assembly 270 is shown that includes a Fresnel lens assembly 200 (e.g., including a reflective polarizer) at least partially located between a first substrate and a second substrate, which can, for example, include glass or a polymer. A first substrate 272 can support the Fresnel lens assembly. A second substrate 274 can provide mechanical protection for the upper surface profile of the Fresnel lens assembly. A gap 276 between the profile substrate and the second substrate can include a filler layer. The filler layer can include a gas (e.g., air, nitrogen, a rare gas (such as argon), or other gas that does not react with the optical material), a liquid, or a solid. In some examples, the solid filler layer can also provide a second substrate, so that a separate second substrate can be omitted. In some examples, the refractive index of the filler layer is significantly different from (e.g., significantly lower than) the refractive index of the optical material used to make the Fresnel lens. In some examples, the second substrate or the first substrate can include a reflective polarizer. In some examples, the filler layer can be used to flatten the faceted surface of the Fresnel lens, and the reflective polarizer can be located on the filler layer.

[0066] In some examples, the Fresnel lens and the filler layer include the same material. In some examples, the Fresnel lens and the filler layer may have matching refractive indices for at least one wavelength (e.g., visible light), but the two materials may have different optical dispersions. In some examples, the Fresnel lens and the filler layer may have substantially different refractive indices. For example, the refractive index of the filler layer may differ from the refractive index of the Fresnel lens by at least about 0.1, 0.2, 0.5, or more.

[0067] In some examples, at least one of the Fresnel lens and the filling layer can have a low birefringence value and can have an optical delay of less than 1 / 4 wavelength (such as less than 1 / 8 wavelength, and in some examples, less than 1 / 16 wavelength) for at least one wavelength of visible light.

[0068] Figure 3 Possible light propagation through a cross section of an example Fresnel lens assembly 300 is shown. Fresnel lens assembly 300 includes Fresnel lens 310, reflective polarizer 315, and filler layer 320. Facets 312 of Fresnel lens 310 support reflective polarizer 315 (indicated by bold lines in the figure). Adjacent facets 312 are separated by steps 318. The reflective polarizer is configured to reflect light of a first polarization and transmit light of a second polarization. Light beam 305 may include light having a first polarization that is reflected by reflective polarizer 315 to form reflected light beam 328, and may include light of a second polarization that is transmitted by reflective polarizer to form transmitted light beam 325.

[0069] Figure 4 A cross section of an example Fresnel lens assembly 400 including a Fresnel lens 410, reflective polarizers 415, 416, 417, a filler layer 420, and an absorptive polarizer 425 is shown. Incident light is shown as a beam of light 405, and reflected light is shown as a beam of light 428. The absorptive polarizer 425 can transmit light of a first polarization reflected by the reflective polarizers 415, 416, and 417. The absorptive polarizer can absorb light of a second polarization that would otherwise be transmitted by the reflective polarizers 415, 416, 417. Steps 418 can be located between adjacent reflective polarizer facets. In some examples, a reflective layer (e.g., a metal film) can be used instead of a reflective polarizer. Stray light (such as light 430 and 435) may be transmitted through the Fresnel lens assembly. In some examples, stray light may pass through gaps between reflective polarizers, such as through gaps between reflective polarizers 416 and 417. Stray light may be generated due to multiple reflections from reflective polarizers and / or other interfaces.

[0070] Figure 5 A cross section of an example Fresnel lens assembly 500 is shown, which includes a Fresnel lens 510, a reflective polarizer 515 located on a facet of the Fresnel lens 510, a filler layer 520, an absorptive polarizer 525, and a second absorptive polarizer 540. Steps 518 can be located between adjacent facets. Incident light rays are shown as ray bundle 505, and reflected light rays are shown as ray bundle 528. The Fresnel lens assembly 500 can be configured as described above with reference to Figure 4 The Fresnel lens assembly 400 described above operates in a similar manner. A second absorbing polarizer 540 can absorb stray light rays, such as light rays 530 and 535 .

[0071] Figure 6 A cross section of an example Fresnel lens assembly 600 is shown, which includes a Fresnel lens 610, a reflective polarizer 615 located on a cut surface of the Fresnel lens 610, a filler layer 620, a first polarizer 625, and a second polarizer 640. In this example, a light ray bundle 605 can be polarized (or further polarized) by the first polarizer 625. The light ray bundle 605 can have a polarization state that is preferentially transmitted by the reflective polarizer 615. The second polarizer 640 can be configured to preferentially transmit the light ray bundle 605 to form a light ray bundle 645.

[0072] FIG. 7A to FIG. 7D The attachment of a reflective polarizer to one or more facets of a Fresnel lens is shown.

[0073] Fig. 7A A manufacturing apparatus 700 is shown that includes a Fresnel lens 705 having facets 708. A reflective polarizer 720 is supported by an elastomeric element 710. The reflective polarizer is divided into portions having sizes corresponding to the facets 708. The elastomeric element 710 is supported by a substrate 740, which may include a rigid element such as a plate. The elastomeric element 710 may be urged toward the Fresnel lens 705 to allow portions of the reflective polarizer 720 to adhere to corresponding facets 708 of the Fresnel lens 705. In some examples, the substrate 740 may be attached to or otherwise in mechanical communication with at least one actuator that is configured to urge the elastomeric element against one or more facets of the Fresnel lens upon receiving an appropriate control signal from a controller.

[0074] Simulations indicate that the reflective polarizer can be adhered to the cut face 708 without creating excessive stress in the reflective polarizer. The von Mises stress in the reflective polarizer during attachment to the Fresnel lens cut face is shown in grayscale with units of 10 8 N / m 2 The stress may be adjusted by adjusting one or more parameters, such as the hardness of the substrate, the hardness of the elastomer, the speed of placement, the provision of a compressible adhesive layer, and the like.

[0075] Figure 7BA portion of a manufacturing apparatus 700 is shown, showing an elastomeric element 710, a reflective polarizer 720, and a Fresnel lens 705. Only a representative facet (of a plurality of facets 708) of the Fresnel lens 705 and a portion of a step 706 separating adjacent facets are shown. Initially, when the reflective polarizer is supported by the surface of the elastomeric element 710, the stress in the reflective polarizer can be approximately zero. In some examples, a portion of the reflective polarizer 720 can be sized to cover at least a portion or substantially all of a corresponding facet in the plurality of facets 708 and may not cover the step 706.

[0076] Figure 7C A portion of the reflective polarizer 720 is shown being pushed against the facet 708 of the Fresnel lens 705 by an upward (as shown) force applied to the elastomeric element 710. There is some stress in a region 722 of the reflective polarizer 720 where the reflective polarizer is actually in the process of being transferred from the elastomeric element 710 to the facet 708 of the Fresnel lens 705. However, the stress is not sufficient to cause any damage to the reflective polarizer.

[0077] Fig.7D It is shown that when the elastic element 710 is Figure 7C When moving further upward in the sectional view of the reflective polarizer 720, the reflective polarizer 720 is completely attached to the cut surface of the Fresnel lens 705. At this stage of formation, the stress in the reflective polarizer is very low. The elastomeric element 710 can have a surface coating that facilitates the release of the reflective polarizer from the elastomeric element 710. The cut surface can have a surface coating that promotes the adhesion of the reflective polarizer to the cut surface of the Fresnel lens 705.

[0078] FIG. 8A to FIG. 8C Also shown is a portion of a manufacturing apparatus 800 that may be used to manufacture a device according to some embodiments.

[0079] Fig. 8A A method of placing a reflective polarizer onto a facet of a Fresnel lens is shown. The figure shows a portion of a manufacturing apparatus 800 showing a portion of a Fresnel lens 805 having facets 808, steps 806, an elastomeric element 810, and a reflective polarizer 820. Portions 822 of the reflective polarizer 820 are shown supported by the elastomeric element 810. Before or after the reflective polarizer is placed on the elastomeric element 810, the reflective polarizer 820 can be patterned into a plurality of portions sized to match and / or conform to the plurality of facets 808.

[0080] Figure 8BThe elastomeric element 810 is shown being moved toward the Fresnel lens using, for example, an actuator. A reflective polarizer 820, such as a reflector polarizer portion 825, is in contact with a cut surface of the Fresnel lens 805. The upper surface of the elastomeric element may include a portion 824 that is not in contact with the Fresnel lens. However, a reflective polarizer may be attached to a Fresnel lens using this method.

[0081] Figure 8C The elastomeric element is shown being moved away from the Fresnel lens. The reflective polarizer is released from the upper surface 826 of the elastomeric element 810 and attached to the cut surface of the Fresnel lens 805. The reflective polarizer 820 can include different portions (e.g., portion 830) that can have the same composition or different compositions.

[0082] FIG. 7A to FIG. 7D and FIG. 8A to FIG. 8C The times shown in can correspond to specific times during an example method of attaching a reflective polarizer portion to a Fresnel lens facet. A time of zero can correspond to the start of a process, e.g., initiating movement of a substrate such as an elastomeric element toward a Fresnel lens, or initiating a simulation of substrate movement. The times shown are exemplary and not limiting.

[0083] The elastomeric element used to support the reflective polarizer during manufacturing may include natural rubber, silicone elastomers, thermoplastic elastomers, polydimethylsiloxane (PDMS), or other types of elastomers. The elastomeric element may include any other soft material and / or structure that can undergo large deformations, such as a structure including a shell filled with a fluid that is at least partially defined by a flexible membrane. In some examples, the polarizer may be supported by a flexible membrane. The fluid pressure may be adjusted (e.g., increased) to push the membrane against the Fresnel lens to adhere the polarizer to the cut surface of the Fresnel lens. In some examples, a flexible membrane, springs, or other elastomeric elements may be used to push the elastomeric element or other structure supporting the polarizer against the Fresnel lens. For example, the polarizer may be supported by a polymer film.

[0084] In some examples, a reflective polarizer supported by an elastomeric element can be divided into multiple portions that are aligned with corresponding facets of a Fresnel lens and are sized to conform to corresponding facets of the Fresnel lens. In some examples, different portions of the reflective polarizer can have the same composition and / or can have similar optical properties. In some examples, different portions of the reflective polarizer can have different optical properties and, for example, can have different compositions. For example, different portions of the reflective polarizer can include different polymers. Different portions of the reflective polarizer can have different optical properties, for example, can have different refractive indices and / or different optical dispersions at a given wavelength. In some examples, a Fresnel lens can be configured as an achromatic lens and include reflective polarizer portions having different optical properties.

[0085] In some examples, the reflective polarizer can include multiple portions sized to conform to multiple facets of a Fresnel lens. The Fresnel lens can have facets that are circular, annular, linear, or cylindrical.

[0086] Fig. 9 A Fresnel lens 900 is shown that includes facets (e.g., facets 905 and 915) and steps (e.g., steps 910 and 920). In this example, the Fresnel lens has substantially linear facets. In some examples, the facets may include circular facets or other facet shapes, such as oval, elliptical, annular, linear (e.g., rectangular), etc.

[0087] Fig.10 A Fresnel lens assembly 1000 is shown, which includes a Fresnel lens 1010, a filler layer 1020 that flattens the upper surface of the Fresnel lens assembly 1000, and reflective polarizer portions 1040 and 1050 disposed on a facet of the Fresnel lens 1010. In this example, the reflective polarizer portions can be generally rectangular. However, the reflective polarizer portions sized to cover the corresponding facets of the Fresnel lens can be any suitable shape. A step 1060 can be located between adjacent reflective polarizer portions 1040 and 1050, and the step may not support the reflective polarizer portions.

[0088] In some examples, a Fresnel lens assembly may include a Fresnel lens having a faceted surface and a non-faceted surface and a reflective polarizer located on the non-faceted surface (e.g., a reflective polarizer located on a planar surface, a concave surface, or a convex surface of the Fresnel lens). In some examples, a filler layer may be used to smooth (e.g., flatten) the faceted surface, and the reflective polarizer may be located on the filler layer. In some examples, the filler layer may have a first surface and a second surface, the first surface conforming to the faceted surface of the Fresnel lens, the second surface being a planar surface or a non-faceted (smooth) curved surface, such as a concave surface or a convex surface. In some examples, the reflective polarizer may be located on the second surface of the filler layer. In some examples, the reflective polarizer may be located on a facet of the Fresnel lens, and the filler layer may be located above the reflective polarizer and the Fresnel lens and may serve as a protective layer. In some examples, the Fresnel lens assembly may include one or more anti-reflection coatings on the faceted surface and / or the non-faceted surface. In some examples, instead of or in addition to applying a reflective polarizer to a faceted surface, a reflective polarizer can be applied to a non-faceted surface. In some examples, a Fresnel lens can have two faceted surfaces, and a reflective polarizer can be applied to at least one of the two faceted surfaces.

[0089] In some examples, the Fresnel lens assembly may include, for example, Fig. 9 and Fig.10 The Fresnel lens shown has a reflective polarizer formed on at least one facet. The example Fresnel lens assembly can be used in conjunction with a photovoltaic device (such as a solar cell) to improve photovoltaic efficiency. In some examples, the Fresnel lens assembly can be configured to transmit visible light (e.g., transmit visible light to the photovoltaic device) and reflect IR radiation (e.g., to reduce heating of the photovoltaic device). For example, the Fresnel lens assembly can include a dichroic filter and / or a reflector (e.g., a reflective polarizer) that can be configured to selectively reflect IR radiation or other wavelength ranges (e.g., a red wavelength range and / or a near IR wavelength range, or other wavelength ranges).

[0090] An example Fresnel lens may also include a peripheral edge, but for lens applications, this edge may not serve as a light receiving surface and may be coated with a light absorbing coating.

[0091] In some examples, a Fresnel lens assembly can include a waveguide having at least a portion of a surface including facets and steps, and at least one waveguide edge can function as a light receiving surface or a light transmitting surface.

[0092] A Fresnel lens assembly can include a Fresnel lens having a planar surface and an opposing surface that includes facets and steps. In some examples, the Fresnel lens can include a curved surface without facets, such as a convex surface or a concave surface. In some examples, the Fresnel lens can include a curved surface with facets and steps. The steps can allow for a reduction in lens thickness and / or an increase in lens optical power for a given lens thickness.

[0093] Fig.11 A Fresnel lens 1100 is shown having a lens body 1105 having a planar surface 1130 and a curved surface 1140, the curved surface including facets (e.g., facets 1110 and 1112) and steps (e.g., step 1106). The steps can be located between adjacent facets. In some examples, a reflective polarizer can be applied to one or more facets. The figure shows only a portion of the reflective polarizer 1120 located on facet 1112, but other facets can also support multiple portions of the reflective polarizer. The Fresnel lens 1100 can be circular (the figure shows a cross-section) and can have a central region including a circular central facet 1150, which is surrounded by a peripheral region 1160, which includes surrounding concentric annular facets. In some examples, the curved surface 1140 can be an aspherical conical surface, and the central facet 1150 can include a relatively large spherical or aspherical surface, and the peripheral region 1160 can include concentric annular facets. A reflective polarizer layer is applied to some or all of the curved surface 1140. The curved surface 1140 may support additional cladding layers, such as partially or highly reflective metal cladding layers, absorbing or reflective polarizers, anti-reflective cladding layers, or combinations thereof.

[0094] A Fresnel lens assembly may include a Fresnel lens and a reflective polarizer that covers both the facets and steps of the Fresnel lens. In some examples, the reflective polarizer may have a first surface and a second surface, the first surface conforming to the facets and steps of the Fresnel lens, the second surface being a flat surface, a spherical surface, a cylindrical surface, an aspherical surface, a conical surface, an aspherical conical surface, other Zernike shaped surfaces, or a combination thereof. The second surface of the reflective polarizer may support another layer (such as an anti-reflective layer or an anti-scratch layer), or may be an outer surface of the assembly. The surface of the Fresnel lens and / or the reflective polarizer may include a diffractive volume Bragg grating or a surface relief grating, and / or other optical elements. The surface and / or layer configuration of the example Fresnel lens and / or the reflective polarizer may be flat, spherical, cylindrical, aspherical, Fresnel-shaped, other Zernike shapes, or a combination thereof.

[0095] Fig.12A Fresnel lens assembly 1200 is shown that includes a Fresnel lens 1205 having a curved surface 1230 and a surface 1210 that includes facets and steps, such as facets 1212 and step 1216. A reflective polarizer 1220 can be located on and conform to the facets of surface 1210. A filled polymer layer 1240 can be located on the reflective polarizer. In this example, a surface 1250 of the filled polymer layer 1240 can include facets and steps, such as facets 1242 and step 1246. The curved surface 1230 can be a concave surface (e.g., a concave spherical surface, a concave parabolic surface, a concave conical surface, or a concave aspherical conical surface), or in other examples, the curved surface can be planar or convex. The figure shows that the steps in the surface 1210 of the Fresnel lens 1205 do not need to be aligned with the steps 1246 in the outer surface of the filled polymer layer. In some examples, the outer surface can be adjacent to air. In some examples, including offsets between steps in different layers can reduce the user's perception of steps.

[0096] Fig.13 A display 1305 and an optical construction 1300 are shown, which can be configured to receive light from the display and direct the light to a target location. The target location can be an eye zone of the head mounted device, and when the user's eye is located within the eye zone, the target location can allow the display to be viewed through the optical construction. The optical construction includes a first Fresnel lens assembly 1310 and a second Fresnel lens assembly 1360.

[0097] The first Fresnel lens assembly 1310 can include a Fresnel lens 1315 having a faceted surface 1324 and a concave surface 1325 and a reflective polarizer 1320 located on the faceted surface 1324 of the Fresnel lens 1315. The reflective polarizer 1320 can conform to the faceted surface of the Fresnel lens. The filling polymer layer 1340 can have a structured outer surface 1350 (facing the display) that is also faceted, and the inner surface can be structured to complement the structured surface of the Fresnel lens. The facets 1342 of the outer surface 1350 of the filling polymer layer 1340 can be wider than the facets of the faceted surface 1324 of the Fresnel lens 1315 (e.g., when comparing facets having approximately similar average radial distances from the optical center of the lens). In some examples, the outer surface 1350 of the filling polymer layer can be a smooth curve, or a facet having dimensions similar to the facets of the Fresnel lens. In some examples, the steps of different faceted surfaces may be offset (e.g., may have different average radii relative to the optical center or axis of the lens). For example, steps 1344 in outer surface 1350 of filled polymer layer 1340 may not be aligned with steps in structured surface 1324 of Fresnel lens 1315.

[0098] The second Fresnel lens assembly 1360 may include a Fresnel lens 1362 and a reflective polarizer 1364 located on a facet of a structured surface 1366 of the Fresnel lens 1362. The second Fresnel lens assembly 1360 also includes a filled polymer layer 1368 having a planar outer surface and facets and steps approximately complementary to the structured surface of the Fresnel lens 1362.

[0099] Example light beam 1370 is shown as a dashed line emitted from display 1305. Light beam 1370 passes through first Fresnel lens assembly 1310 and is reflected back by second Fresnel lens assembly 1360. In some examples, a reflector and / or beam splitter may be used instead of the polarizing reflector shown. The light beam may be reflected from a reflector (e.g., a beam splitter) or a polarizing reflector within each Fresnel lens assembly. The light beam is reflected back by first Fresnel lens assembly 1310 and is transmitted through second Fresnel lens assembly 1360. The light beam may then exit optical construction 1300 to be directed toward a user's eye (not shown, but the user's eye may be positioned toward the right side of the optical construction).

[0100] In some examples, the polarizing reflector can be located between the Fresnel lens and the filled polymer layer (if present), and in some examples, the reflective polarizer can be located only on the cut facets of the Fresnel lens and not on the steps. In some examples, the relative positions of the Fresnel lens, the reflective polarizer, and the filled polymer layer (if present) within the Fresnel lens assembly as described herein can be reversed or otherwise rearranged.

[0101] Fig.14 Another example Fresnel lens assembly 1400 is shown including a Fresnel lens 1410 having a planar surface 1415 and a faceted surface 1420. Faceted surface 1420 supports a reflective polarizer 1430. In some examples, the reflective polarizer may be located only on facets 1424 and not on steps 1422. A filled polymer layer 1440 may conform to faceted surface 1420 (and the reflective polarizer 1430 disposed therein) and may be formed with an outer surface 1450. The outer surface 1450 may include steps (such as step 1442) and facets 1444. In this example, the filled polymer layer is configured as a lens having a faceted outer surface, which is configured as a concave lens including, for example, a concave facet (such as a central concave facet 1446). In some examples, the reflective polarizer may be replaced by a reflector or a beam splitter.

[0102] In some examples, the Fresnel lens may include a reflective polarizer formed as a layer on one or more of the lens facets. The reflective polarizer may include an arrangement of a multilayer optical film, a cholesteric liquid crystal, or an anisotropic conductor. The facets and the coating may be embedded in an optically transparent layer, such as a filling polymer. The refractive index and optical dispersion of the Fresnel lens material and the filling polymer may be selected to reduce chromatic aberration (e.g., color fringes in an image). In some examples, the optical material (e.g., an optical material for a Fresnel lens) may have a low birefringence (e.g., corresponding to an optical delay of less than a quarter wavelength). In some examples, the Fresnel lens and / or the filling polymer may include a silicone polymer (e.g., polydimethylsiloxane (PDMS)), a cyclic olefin polymer (COP), a cyclic olefin copolymer (COC), a polyacrylate, a polyurethane, or a polycarbonate. For example, a PDMS Fresnel lens may be supported on a rigid substrate (e.g., glass). Vapor deposition of the coating may result in unwanted deposition on the facades between the facets. An elastic substrate can be used to selectively position an appropriately segmented coating on a tangent plane of a Fresnel lens. A reflective polarizer supported by a Fresnel lens can be used in an augmented reality and / or virtual reality (AR / VR) system. Other components may include a display and a beam splitter. In some examples, an AR / VR system may include a beam splitter supported by a Fresnel lens, and the lens may be optimized individually. The Fresnel lens may be concave, convex, or may have a complex optical profile (such as a free surface). Wavelength-dependent properties may be adjusted, for example, by adjusting the multilayer film construction. Applications may also include, for example, IR suppression in imaging systems, display systems, or photovoltaic systems.

[0103] In some examples, the reflective polarizer can conform to the facets of the Fresnel lens. The facets can be generally planar, or in some examples, the facets can be curved to provide a portion of a surface curvature of a concave, convex, aspherical, cylindrical, free-standing lens, or any other lens. In some examples, the filling polymer layer can be formed after the reflective polarizer is adhered to the facets of the Fresnel lens. In some examples, the reflective polarizer can be a layer sandwiched between the Fresnel lens and an optical element (e.g., a second lens) formed by the filling polymer. The method of manufacturing a Fresnel lens assembly can include placing a reflective polarizer on the facets of the Fresnel lens and then forming a second lens on the reflective polarizer and any portion of the portion of the Fresnel lens surface that does not support the reflective polarizer (e.g., a step between the facets, which step is sometimes referred to as a facade).

[0104] In some examples, an optical configuration including at least one Fresnel lens assembly (e.g., as described herein) can allow for improved device efficiency, particularly for AR / VR applications. For example, an image for a display can be formed using light beams within +20 degrees / -20 degrees of a principal ray (which typically corresponds to light emitted orthogonally to a display surface). Example displays include light-emitting diode (LED) displays (such as organic LED (OLED) displays), which are generally more efficient for imaging using these approximately on-axis rays.

[0105] The Fresnel lens assembly 1400 can be configured in other arrangements. In some examples, the Fresnel lens assembly 1400 can include a Fresnel lens 1410 including a first polymer and a second Fresnel lens (the second Fresnel lens is formed, for example, from a filled polymer layer 1440), and the Fresnel lens 1410 includes a first polymer and the second Fresnel lens can include a second polymer. The optical properties of the first polymer and the second polymer can be configured to reduce chromatic aberration of the Fresnel lens, for example by having different optical dispersions (e.g., wavelength-dependent refractive index values). An example reflective polarizer can include a layer formed on a faceted interface between two Fresnel lenses (e.g., a layer formed on or near the faceted surface 1420), or a layer formed on any other faceted surface of one or both Fresnel lenses. For example, one Fresnel lens or two Fresnel lenses in a plurality of Fresnel lenses can support a reflective polarizer using any suitable method, and then the two lenses can be combined together so that in some examples, the reflective polarizer is located at the interface between the two lenses.

[0106] Fig.15 An optical configuration 1500 is shown that includes a first Fresnel lens assembly 1520 (which may be the same as described above with respect to Fig.14 Similar to the Fresnel lens assembly 1400 discussed above, the first Fresnel lens assembly includes a Fresnel lens 1510 and a reflective polarizer 1530 and a second Fresnel lens assembly 1540 (the second Fresnel lens assembly can be the same as described above with respect to Fig.13 1500). Optical construction 1500 may also include optical film 1550, which may include an optical retarder. Optical construction 1500 may be configured to receive light from display 1505 (which may include, for example, representative light beam 1506). The propagation of light from the display through the optical construction may be similar to that described above with respect to Fig.13When a user wears an exemplary apparatus including the optical construction, such as a head mounted device, light from display 1505 can pass through optical construction 1500 and through surface 1545 toward the user's eyes.

[0107] Fig.16 Various possible beam directions within the optical construction are qualitatively shown. This figure is for illustrative purposes only and is not limiting, and includes possible directions of multiple reflected beams and / or stray beams. Optical construction 1600 can receive light from display 1605 (as shown by the representative beams represented by dashed lines), which includes a first beam of rays 1650 from an edge portion of display 1605 and a second beam of rays 1655 from a center portion of display 1605. The light from the display can pass through a first Fresnel lens assembly 1630 and a second Fresnel lens assembly 1640. Each Fresnel lens assembly can include a combination of a Fresnel lens and a reflective polarizer. For example, reflective polarizer 1637 (or a beam splitter in some examples) can be located at the right hand surface of first Fresnel lens assembly 1630 (as shown). In some examples, reflective polarizer 1645 can be located at the right hand surface of second Fresnel lens assembly 1640 (as shown). Optical film 1635 can represent an optical retarder, and in some examples, the positions of the optical retarder and the reflective polarizer can be interchanged. Line 1660 may represent the focal plane of the image of the display. Triangle 1670 may be a schematic representation of a possible location of the eye zone. In this example, the eye zone may represent the approximate location where the user's eyes may be located to view the display.

[0108] In some examples, a method may include: forming a reflective polarizer on a substrate; patterning the reflective polarizer to form a reflective polarizer portion sized to match a corresponding facet of a Fresnel lens; and applying the reflective polarizer portion to the corresponding facet of the Fresnel lens. Example methods may include methods of manufacturing and / or using an optical element or an apparatus including an optical element. The reflective polarizer portion may be sized or patterned using laser ablation or any other suitable method to remove a portion corresponding to a stepped portion (sometimes referred to as a draft surface) of the Fresnel lens. Applying the reflective polarizer portion to the corresponding portion of the Fresnel lens may include using a force applied to the substrate to push the reflective polarizer portion against the corresponding facet of the Fresnel lens. Forming the reflective polarizer on the substrate may include forming the reflective polarizer on an elastomeric element. Pressure may be applied using air pressure to expand the substrate to apply a uniform force to the Fresnel facet. For example, the polarizer may be formed on an elastomeric element or other substrate, such as a polymer film. In some examples, the polymer film may be an elastomeric element (e.g., a polymer film including a polymer elastomer). The example method may also include removing the substrate so that the reflective polarizer portion remains bonded to the corresponding portion of the Fresnel lens. The reflective polarizer may be adhered to the substrate using a UV reversible adhesive or a thermal reversible adhesive. After adhering the reflective polarizer to the Fresnel facet, the substrate may be removed by applying UV irradiation or thermal stripping, and after evacuating the substrate, the reflective polarizer may remain adhered to the faceted surface of the Fresnel lens.

[0109] Fig.17 An example method 1700 for making a Fresnel lens assembly is shown. The method includes: forming a reflective polarizer portion on a supporting substrate (elastomer in this example) by bonding the reflective polarizer to the elastomer (1705); coating and patterning an etch stop on the reflective polarizer (1710); etching the reflective polarizer into the reflective polarizing portion (1715); and removing the etch stop (1720). After these process steps, a reflective polarizer portion sized to match a corresponding facet of a Fresnel lens can be supported by a substrate (such as an elastomer). For example, the reflective polarizer portion can include a central circular portion surrounded by concentric annular portions. The example reflective polarizer portion can surround a central portion (e.g., a reflective polarizer portion adhered to a central circular facet of a Fresnel lens), can be substantially concentric, and the portion configuration (e.g., shape and size) can correspond to the configuration of a corresponding facet of a Fresnel lens.

[0110] The method 1700 may further include providing a Fresnel lens coated with an adhesive layer on a cut surface of the Fresnel lens by forming a Fresnel lens (1725) and coating the Fresnel lens with an adhesive layer (1730).

[0111] Method 1700 may also include positioning a reflective polarizer portion on a facet of the Fresnel lens by aligning the reflective polarizer portion with a corresponding facet of the Fresnel lens (1740); pushing (e.g., pressing) the reflective polarizer portion against the corresponding facet of the Fresnel lens (1750); and removing a substrate (e.g., an elastomer) from the reflective polarizer (1760) to leave the reflective polarizer portion attached to the facet via the adhesive layer. In some examples, a heating step or a UV irradiation step may be used to remove the substrate. An optional protective coating (1770) may be applied to the Fresnel lens, for example, the Fresnel lens including a filled polymer or including the protective coating in addition to the filled polymer. In some examples, the protective coating may provide, include, or be a component of a filled layer. An example protective coating (e.g., a filled layer) may include an optically transparent polymer. The method provides a Fresnel lens assembly comprising a Fresnel lens and a reflective polarizer (1780) located at least on one or more cut surfaces of the Fresnel lens, wherein optionally, the method may also include applying or otherwise including one or more additional layers (e.g., anti-reflective coatings, additional reflective layers, optically absorbing layers, optically absorbing polarizers, scratch-resistant layers, lenses, etc.).

[0112] Fig.18 An example method of making a Fresnel lens assembly including a Fresnel lens and a reflective polarizer is shown. The method (1800) includes: forming a reflective polarizer on a substrate (1810); patterning the reflective polarizer (1820) to form a portion of the reflective polarizer sized to match a facet of the Fresnel lens; and applying a portion of the reflective polarizer to a corresponding portion of the Fresnel lens (1830). This may include using a substrate (such as a substrate including an elastomeric element) to push the reflective polarizer against a faceted surface of the Fresnel lens. The substrate may then be removed so that the reflective polarizer remains attached to the Fresnel lens. The substrate may be removed by any suitable method, including physical movement (e.g., pulling the substrate away from the Fresnel lens to leave the reflective polarizer supported by the Fresnel lens), ablation, etching, heating, melting, vaporization, sublimation, burning, irradiation (e.g., by UV radiation), or any other suitable physical and / or chemical method (or combination of methods) of removing the substrate or a combination thereof.

[0113] Fig.19A method of making a Fresnel lens assembly including a Fresnel lens and a reflective polarizer is shown. The method (1900) includes: forming a reflective polarizer on an elastomeric element (1910); using the elastomeric element to push the reflective polarizer against a surface of the Fresnel lens (1920); and removing the elastomeric element so that the reflective polarizer remains attached to the Fresnel lens (1930).

[0114] In some examples, the reflective polarizer can be formed as a layer and then die-cut or otherwise processed to form appropriately sized reflective polarizer portions. The portions can be sized to match corresponding facets of the Fresnel lens. The reflective polarizer layer can be separated into multiple portions using methods such as laser ablation, die-cutting, etching, photolithography, mechanical scribing, or any suitable method. In some examples, the reflective polarizer can be formed on an elastomeric element.

[0115] In some examples, the reflective polarizer may not be divided into multiple parts. For example, the reflective polarizer may be thermoformed or otherwise attached to the Fresnel lens, and regions of the reflective polarizer may be removed (e.g., from steps between facets), for example, using patterned refractive ion etching, diamond machining, etc.

[0116] In some examples, Fig.17 The arrangement of the method described and steps 1740 to 1760 may be implemented by, for example, FIG. 8A to FIG. 8C The arrangement discussed above may be performed and may include, for example, FIG. 8A to FIG. 8C The components discussed are implemented by a device manufacturing apparatus.

[0117] In some examples, a method of manufacturing a Fresnel lens assembly including a reflective polarizer and a Fresnel lens includes the steps of providing a structured transparent substrate, wherein at least one side of the substrate has at least two facets separated by a facade, wherein a reflective polarizer layer is bonded to the facet of the structured substrate. The reflective polarizer can be supported by an elastomeric element, and the reflective polarizer can be transferred to the facet of the Fresnel lens by applying pressure (e.g., including applying a force to the elastomeric element and / or the Fresnel lens to push the reflective polarizer against the facet of the Fresnel lens). In some examples, before applying pressure, an adhesive layer is coated on at least the facet of the Fresnel lens and / or the reflective polarizer. For example, the surface of the reflective polarizer that is pushed into contact with the facet of the Fresnel lens can have an adhesive layer. The adhesive can include a pressure-sensitive material, a heat-activated material, or a light-curable material.

[0118] In some examples, the reflective polarizer can be patterned to align with the facet of the Fresnel lens. The patterned reflective polarizer can be formed on an elastomeric element, aligned with the facet, and then the elastomeric element can be moved (e.g., by an actuator) so that the patterned reflective polarizer is urged into contact with the facet of the Fresnel lens.

[0119] The reflective polarizer may be less strongly bonded to the elastomer than to the facet, such that when the elastomeric element is withdrawn from the facet, the reflective polarizer remains adhered to the facet. In some examples, the reflective polarizer may be removed (e.g., unbonded) from the elastomer using a peeling process such as laser peeling. Laser peeling may include a process for separating two layers of material in which a thin layer is present at the interface between the two layers that can be ablated by laser radiation (e.g., from a pulsed or scanned laser).

[0120] In some examples, a method of making a Fresnel lens assembly including a Fresnel lens and a reflective polarizer includes providing a substrate having at least two adjacent facets separated by a step (sometimes referred to as a facet); and conforming a reflective polarizing film to the faceted substrate and bonding the reflective polarizing film to the faceted substrate. The method may also include removing the reflective polarizer film from the facet.

[0121] In some examples, the reflective polarizer can be manufactured by applying an alignment layer (e.g., a polymer layer or a grating) and applying at least one layer of cholesteric liquid crystal (CLC), which is at least partially aligned with the alignment layer. The alignment layer may include a photoalignment material (PAM) that can be placed on a substrate, and the desired molecular orientation can be obtained by exposing the PAM to polarized light (e.g., ultraviolet (UV) light and / or visible light). The CLC can be further processed to lock the molecular alignment of the CLC into a solid material, for example, to provide a chiral material (e.g., a chiral solid). For example, the CLC can be polymerized or cross-linked, or a polymer network can be formed by the CLC to stabilize the alignment, thereby providing a chiral solid. If a CLC phase is used in the preparation of the chiral solid, the chiral solid can be referred to as a CLC-based material. In some examples, the CLC can be formed using an effective concentration of a chiral dopant in a nematic liquid crystal, and the chiral nematic (cholesteric) mixture can also include a polymerizable material.

[0122] In some examples, the reflective polarizer may include a chiral material, such as a material having a molecular order similar to that of a cholesteric liquid crystal, such as a solid material obtained by cooling, polymerizing, cross-linking, or otherwise stabilizing the molecular order of the cholesteric liquid crystal. For example, the chiral solid may be a solid having a helical optical structure similar to that of a cholesteric liquid crystal. For example, the direction of maximum refractive index may describe a helix about a normal to a local direction of molecular orientation.

[0123] In some examples, the reflective polarizer may include a birefringent multilayer optical film that may be conformed to a faceted substrate (eg, of a Fresnel lens) through a combination of heat and pressure.

[0124] In some examples, the polarizing beam splitter may include a transparent lens having a first surface and a second surface, wherein the first surface is a Fresnel lens and the second surface is adjacent to the reflective polarizing layer. At least one of the first surface and the second surface may have a cylindrical curvature, a spherical curvature, or an aspherical curvature.

[0125] Fig. 20 An example operating method (2000) is shown, which can be performed, for example, by an apparatus, such as a head mounted device (such as an AR / VR device). The method can include: emitting light from a display (the light, for example, including one or more light rays) (2010); transmitting the light through a first Fresnel lens assembly (2020); reflecting the light from a second Fresnel lens assembly (2030); and reflecting the light from the first Fresnel lens assembly so that the light passes through the second Fresnel lens assembly and toward an eye zone (2040), for example, where the user can view an image of the display when the user wears the device. The user's eye can be located at the eye zone (e.g., where the display image is formed) to view the image of the display. The first Fresnel lens assembly can include a first Fresnel lens and a first reflective polarizer. The second Fresnel lens assembly can include a second Fresnel lens and a second reflective polarizer.

[0126] In some examples, an optical retarder may be located between the first and second Fresnel lens components, and light from the display may pass through the optical retarder multiple times (e.g., three times) before being transmitted through the second Fresnel lens component toward the user's eye. In some examples, light having a polarization, such as linear polarization or circular polarization, may be emitted from the display. Each time the light passes through the optical retarder, the polarization may be changed by the optical retarder. Reflection may also change the polarization of the light. For example, light from the display (e.g., polarized light) may be transmitted through the first Fresnel lens component, through the optical retarder, reflected by the second Fresnel lens component, through the optical retarder, reflected by the first Fresnel lens component, through the optical retarder, and then transmitted by the second Fresnel lens component toward the user's eye, wherein the light may be incident on the reflective polarizer with a first linear polarization, which may be reflected by the reflective polarizer of the second Fresnel lens component. Light may be reflected from the reflective polarizer of the first Fresnel lens component and then may be transmitted by the reflective polarizer. In some examples, at least one of the Fresnel lens assemblies can include an optical retarder, and a separate optical retarder can be omitted from the optical construction.

[0127] In some examples, providing image brightness using an optical configuration by a display (e.g., including a display panel) may include spatially adjusting a spatial profile of illumination brightness of a light source (e.g., a backlight) and / or an emissive display. The display brightness may be adjusted based on one or more display parameters, such as spatial position on the display (e.g., spatial variation of image brightness), power consumption, aging effects, eye response functions, and / or one or more other parameters.

[0128] In some examples, a method may include: emitting light having circular polarization or linear polarization from a display; transmitting the light through a first Fresnel lens assembly; reflecting the light from a second Fresnel lens assembly; and reflecting the light from the first Fresnel lens assembly so that the light passes through the second Fresnel lens assembly and toward an eye of a user. The device may be configured such that light is transmitted through the first Fresnel lens assembly with a first polarization and is reflected by the second Fresnel lens assembly with a second polarization. This may be accomplished using an optical retarder located between the first Fresnel lens assembly and the second Fresnel lens assembly and / or using a change in polarization upon reflection. The display may emit polarized light itself, or in some examples, a suitable polarizer may be associated with (e.g., attached to) a surface through which light from the display is transmitted.

[0129] Example methods include computer-implemented methods for operating an apparatus, such as an apparatus described herein, such as a head-mounted display, or an apparatus for manufacturing a Fresnel lens assembly. The steps of the example methods may be performed by any suitable computer executable code and / or computing system, including apparatus such as an augmented reality system and / or a virtual reality system. In some examples, one or more steps of the example methods may represent an algorithm whose structure includes and / or may be represented by a plurality of sub-steps. In some examples, a method for providing uniform image brightness from a display using a folded optical construction may include using a display panel configured to allow spatial variations in display brightness. In this case, light from the display may be reflected at least once (e.g., twice) within the folded optical construction before reaching the user's eye.

[0130] In some examples, an apparatus (such as a head mounted device or system) may include at least one physical processor and a physical memory including computer executable instructions that, when executed by the physical processor, cause the physical processor to generate an image on a display. The image may include virtual reality image elements and / or augmented reality image elements. The apparatus may include an optical configuration such as described herein.

[0131] In some examples, a non-transitory computer-readable medium may include one or more computer-executable instructions that, when executed by at least one processor of an apparatus (e.g., a head-mounted device), cause the apparatus to provide an augmented reality image or a virtual reality image to a user (e.g., a wearer of the head-mounted device). The apparatus may include an optical configuration such as described herein.

[0132] The Fresnel lens assembly may include a Fresnel lens and a reflective polarizer. For example, at least one facet of the Fresnel lens may support a reflective polarizer. The Fresnel lens may include multiple facets and steps formed in an otherwise planar surface, a cylindrical surface, a free surface, a surface at least partially defined by a Zernike function, or a spherical surface. The Fresnel lens assembly may include additional components, such as a substrate, a filled polymer layer, or any suitable optical element.

[0133] In some examples, the Fresnel lens assembly can include a Fresnel lens and a reflective polarizer. In some examples, the reflective polarizer can be supported by a cut surface of the Fresnel lens (e.g., placed on the cut surface, adhered to the cut surface, or otherwise supported by the cut surface).

[0134] In some examples, the reflective polarizer may include a cholesteric liquid crystal, a birefringent multilayer optical film, or a wire grid. In some examples, the reflective polarizer may include an arrangement of multiple conductive elements, such as wires, rods, tubes, or other conductive elements. The conductive element may include at least one metal (e.g., copper, gold, silver, or other metal, or alloys of the above metals), a conductive carbon allotrope, a doped semiconductor, and the like. In some examples, the reflective polarizer may include a birefringent multilayer film, and one or more surface layers may have a pass polarization refractive index within 0.2 of the average refractive index of the multilayer film, and in some examples, the refractive index of one or more surface layers may differ from the average refractive index of the multilayer film by at least about 0.02, such as at least about 0.05, for example, at least about 0.1. In some examples, the reflective polarizer may include a multilayer assembly including at least one optically isotropic layer adjacent to (e.g., alternating with) a birefringent (e.g., uniaxial) polymer layer. The layers may be substantially parallel and may conform to an underlying optical element that may be used as a substrate. The optically isotropic polymer layer may include an optically transparent polymer. The birefringent polymer layer may include an anisotropic polymer layer, such as a stretched polymer layer or a polymer layer that is otherwise at least partially molecularly aligned. For example, the polymer layer may be stretched by a factor between 1.5 and 10 (e.g., stretched by a ratio between 1.5:1 and 10:1, where the ratio represents the ratio of the final extent to the initial extent along a particular direction).

[0135] In some examples, a Fresnel lens assembly including a reflective polarizer may further include a filling layer. The filling layer may include an optically transparent layer located on a structured surface of the Fresnel lens assembly. For example, the filling layer may conform to the facets and steps of the structured surface (e.g., of a Fresnel lens) and have a second surface without facets or steps, such as a substantially smooth surface. For example, the filling layer may have a planar surface, a concave surface, or a convex surface, which may also be an outer surface or support one or more additional layers, such as an anti-reflective layer or other optical layer. The reflective polarizer may be formed on a facet of a structured optical element such as a Fresnel lens. In some examples, the reflective polarizer may include a multilayer reflective polarizer including at least one birefringent layer. In some examples, the reflective polarizer may include one or more polymer layers and / or one or more inorganic layers.

[0136] In some examples, a structured optical element may include a substrate having a surface including facets and steps, wherein the steps are located between adjacent (e.g., adjacent or substantially adjacent) facets. A reflective polarizer may be positioned adjacent to and conforming to at least a portion of the faceted surface. In some examples, the faceted surface may correspond to a surface portion of a refractive lens (such as a convex surface or a concave surface) and may be curved. In some examples, the facets may be planar and may approximate a surface portion of a refractive lens. For example, a planar faceted surface may have an orientation relative to the optical axis of the lens that varies with an average (e.g., median) radial distance of the facet from the optical center of the lens. In this case, the structured optical element may include surface facets separated by steps, and at least one facet of the Fresnel lens may support a reflective polarizer. Then, a filler material may coat a surface of the Fresnel lens assembly (e.g., including facets, steps, and a reflective polarizer). The filler layer may have a first surface and a second surface (e.g., an outer surface), the first surface having a contour complementary to the Fresnel lens assembly, and the second surface may be a planar surface. In some examples, the second surface of the filling material may have a curved surface, such as a convex surface, a concave surface, a cylindrical surface, a free surface, or other curved surface, or in some examples, the second surface of the filling material may include a second Fresnel lens structure.

[0137] In some examples, the reflective polarizer layer can have an average refractive index for the passed polarization, and the refractive index of the fill layer can differ from the average refractive index of the reflective polarizer by less than 0.2, for example less than 0.1, such as less than 0.05, for example less than 0.02.

[0138] In some examples, the steps between facets can have a step height and / or draft angle that can vary based on the position within the optical element, such as, for example, the radial distance from the optical center of the lens. In some examples, the gap between adjacent reflective polarizer segments can vary based on the position within the optical element, such as, based on the radial distance from the optical center of the lens.

[0139] In some examples, an apparatus (e.g., a head-mounted device, such as an AR and / or VR device) may include an optical structure that includes a pancake lens (e.g., a combination of a lens and a beam splitter, which may also be referred to as a beam splitter lens) and a reflective polarizer. An exemplary reflective polarizer may be configured to reflect light of a first polarization and transmit light of a second polarization. For example, the reflective polarizer may be configured to reflect circularly polarized light of one handedness (e.g., right-handed or left-handed) and transmit circularly polarized light of another handedness (e.g., left-handed or right-handed, respectively). For example, the reflective polarizer may be configured to reflect linearly polarized light in one direction (e.g., a vertical direction) and transmit linearly polarized light in an orthogonal direction (e.g., a horizontal direction). In some examples, the reflective polarizer may be adhered to a cut surface of a Fresnel lens.

[0140] The optical configuration may be referred to as a folded optical configuration, and in this case, the folded optical configuration may provide an optical path including one or more reflections and / or other beam redirections. A device having a folded optical configuration may be compact, have a wide field of view (FOV), and allow for the formation of high-resolution images. Higher lens system efficiency may be useful for applications such as head-mounted displays (HMDs), including virtual reality applications and / or augmented reality applications.

[0141] An example apparatus (which may also be referred to as a device) may include a display, a pancake lens (e.g., the pancake lens includes a beam splitter or a polarizing reflector that may be formed as a coating on a surface of the lens), and a reflective polarizer (e.g., the reflective polarizer is configured to reflect light of a first polarization and transmit light of a second polarization, wherein the first polarization and the second polarization are different). For example, the reflective polarizer may be configured to reflect circularly polarized light of one handedness and transmit circularly polarized light of another handedness.

[0142] Folded optical constructions can be compact, have a wide field of view (FOV), and provide higher resolution for a given distance between the display and the viewer. However, a folded optical construction including a pancake lens may have lower efficiency than a non-folded optical construction including a refractive lens but not including a reflective element. For example, for applications in head-mounted displays (HMDs), the system efficiency of the optical construction is important. Reduced efficiency may reduce the usability of AR / VR devices and may cause discomfort due to increased temperature caused by increased power consumption required for the display to provide the desired image brightness. In some examples, a pancake lens including a beam splitter is used to improve system efficiency, the beam splitter having a higher reflectivity toward the edge of the beam splitter than in the central region of the beam splitter. The lens efficiency can be improved using a polarization conversion beam splitter lens, which includes a beam splitter having a higher reflectivity toward the edge of the lens than in the central region of the lens. In some examples, a pancake lens may include a refractive lens and a beam splitter, which may be formed as a reflective cladding located on the surface of the lens. The reflective cladding may have a reflectivity that varies spatially. In some examples, the pancake lens can include a polarization converting beam splitter lens.

[0143] In some examples, the reflective polarizer may include a cholesteric liquid crystal (such as a polymer cholesteric liquid crystal). In some examples, the reflective polarizer may include a birefringent multilayer reflective polarizer. In some examples, the apparatus may also include an optical retarder, such as a quarter-wave retarder, located between the beam splitter and the reflective polarizer.

[0144] Example reflective polarizers (or other polarizers) can include polarizing films.Example polarizing films can include one or more layers, such as an optical polarizer including a combination of a reflective polarizer and a dichroic polarizer, for example, bonded together.

[0145] In some examples, a Fresnel lens assembly can include a Fresnel lens and a beam splitter (e.g., instead of or in addition to the polarizing reflector shown in various examples herein). The beam splitter can be configured to reflect a first portion of incident light and transmit a second portion of incident light. In some examples, a beam splitter lens can be used with a Fresnel lens assembly. The beam splitter can be formed on a facet of a Fresnel lens using a method adapted from the methods described herein. For example, the beam splitter can be formed on an elastomeric element. The beam splitter can be formed on a substrate and patterned to form a portion sized to match a facet of a Fresnel lens.

[0146] The reflective layer may be formed by one or a combination of processes including thin film physical vapor deposition, chemical vapor deposition, or other suitable processes for depositing a reflective layer such as a highly reflective thin film coating and / or a partially reflective thin film coating. An example reflective layer may include one or more metals such as aluminum or silver, and may be metal-containing. An example reflective layer may include one or more dielectric materials such as silicon dioxide, aluminum oxide, hafnium oxide, titanium dioxide, magnesium oxide, magnesium fluoride, indium tin oxide, and indium gallium zinc oxide, and mixtures thereof. An example reflective layer may include one or more dielectric layers, and may include a Bragg grating structure or a similar multilayer structure.

[0147] An example beam splitter may include one or more regions having different transmittances and / or reflectivities, and may include one or more reflective layers. An example beam splitter may include a first region and a second region, the first region and the second region having different reflectivities, for example, for visible light or at least one visible wavelength of light. The beam splitter may include a coating formed on the surface of the lens, such as a metal coating and / or a dielectric coating (such as a dielectric multilayer). In some examples, the reflectivity of the beam splitter may vary depending on the spatial position within the beam splitter. For example, the beam splitter may include a first region having a first reflectivity and a second region having a second reflectivity. In some examples, the reflectivity of the beam splitter toward the edge of the beam splitter may be higher than the reflectivity within the central region of the beam splitter.

[0148] An example beam splitter may include a partially transparent and partially reflective coating. An example beam splitter may include a thin coating comprising a metal such as gold, aluminum, or silver. The coating thickness of the thin coating may be in the range of about 10 nm to about 500 nm. An example beam splitter may include one or more layers, such as a dielectric film layer. In some examples, the beam splitter may include at least one dielectric material, such as silicon dioxide, aluminum oxide, hafnium oxide, titanium dioxide, magnesium oxide, magnesium fluoride, etc., as a dielectric layer or a component of a dielectric layer. An example beam splitter may include a coating comprising at least one thin metal coating and / or at least one dielectric coating. An example beam splitter may include at least one of a conductive material (e.g., a metal, a conductive metal oxide (such as indium tin oxide or indium gallium zinc oxide) or other conductive material) and a dielectric material, and may include a combination of a conductive material and a dielectric material (e.g., as a coating comprising at least one layer).

[0149] In some examples, the beam splitter can be formed on a convex surface, a planar surface, or a concave surface of the lens. In some examples, the lens can include a Fresnel lens. In some examples, the polarizing reflector can be configured to act as a beam splitter and can, for example, be configured to reflect a first percentage of light of a first polarization and a second percentage of light of a second polarization (wherein the first percentage and the second percentage can be different) while transmitting some, most, or substantially all of the non-reflected light.

[0150] An example reflector (e.g., a beam splitter, a polarizing reflector, or other reflector) may include at least a first region and a second region, wherein the first region may include a central region of the reflector and the second region may include a peripheral region of the reflector. In some examples, the reflector (e.g., a beam splitter or a polarizing reflector for a specific polarization) may have a reflectivity of about 100%, about 95%, about 90%, about 85%, about 80%, about 75%, about 70%, or the reflectivity of the reflector is within a range between any two of these example reflectivity values. For example, the second region may have a reflectivity between about 75% and about 100%, such as a reflectivity between about 85% and about 100%. In some examples, the second region may have a higher reflectivity than the first region, such as a reflectivity of the second region that is at least 10% higher than the reflectivity of the first region. In some examples, the relationship between reflectivity and distance may be a monotonically smooth curve. In some examples, the relationship between reflectivity and distance may be discontinuous or include a transition region with a relatively high rate of change in reflectivity. In some examples, the reflectivity of the beam splitter can gradually transition from the first region to the second region within the transition region. The transition region can have a width (which can be referred to as a transition distance) that can be less than about 5 mm, such as less than 2 mm, such as less than 1 mm. In some examples, the width of the transition region can be less than 0.1 mm, such as less than 0.01 mm.

[0151] In some examples, the reflector (e.g., a beam splitter or a polarizing reflector) may include a partially transparent and partially reflective layer. In some examples, the reflector may include a metal film formed on a substrate, such as a substrate including one or more optical materials. For example, the layer may include a metal layer (e.g., the thickness of the metal layer is between about 5nm and about 500nm, such as the thickness of the metal layer is between 10nm and 200nm), such as a layer including one or more metals (such as aluminum, silver, gold, or other metals (such as alloys)). The layer may include multiple layers and may include an anti-corrosion layer (e.g., located on the metal layer) supported by the exposed surface of the layer. In some examples, the layer may include one or more dielectric layers, such as a dielectric film layer. The dielectric layer may include one or more dielectric layers, such as an oxide layer (e.g., a metal oxide layer or other oxide layer), a nitride layer, a boride layer, a phosphide layer, a halide layer (e.g., a metal halide layer, such as a metal fluoride layer) or other suitable layers. In some examples, the device may include one or more metal layers and / or one or more dielectric layers. The substrate may comprise glass or an optical polymer.

[0152] In some examples, an apparatus may include a display, at least one Fresnel lens assembly including a polarizing reflector, and optionally a beam splitter lens including a beam splitter. The reflectivity of the beam splitter and / or the polarizing reflector may vary depending on the spatial location; for example, the spatial location includes a first region with relatively high light transmittance and a second region with relatively low light transmittance (e.g., relatively high reflectivity). In this case, the segmented reflector may have at least two regions with different optical properties, such as, for example, multiple regions with different reflectivity values ​​for one or more visible wavelengths.

[0153] In some examples, the device may include a reflector having a reflectivity from the first region to the second region with a gradual transition or an actual discontinuous transition. The transition region may be located between the first region and the second region. When measured along a particular direction (e.g., a radial direction orthogonal to the periphery of the first region, or other directions), the transition region may extend over a transition distance between the first region and the second region. In some examples, the length of the transition distance is approximately or less than 5 mm, 1 mm, 0.1 mm, or 0.01 mm.

[0154] In some examples, the reflector can provide selective reflection within a specific wavelength range and / or for a specific polarization. For example, the reflector can include a Bragg reflector, and the layer composition and / or dimensions can be configured to provide a desired operating bandwidth.

[0155] In some examples, the reflector may be formed on an optical substrate such as a lens, and the combination of the lens and the reflector may be referred to as a reflector lens. The reflector lens may include an optical element having at least one curved surface. The reflector may include a reflective cladding formed on or otherwise supported by a planar surface or a curved surface of an optical element such as a lens.

[0156] During the manufacture of the reflector, different reflector regions with different optical reflectivity values ​​may be defined by a mask deposition process or using photolithography or a combination thereof.

[0157] In some examples, a lens (such as a Fresnel lens) may include a surface such as a concave surface, a convex surface, or a planar surface. In some examples, the device may include one or more converging lenses and / or one or more diverging lenses. The optical construction may include one or more lenses and may be configured to form an image of at least a portion of the display at an eye-friendly zone. The device may be configured so that when a user wears the device, the user's eyes are located within the eye-friendly zone. In some examples, the lens may include a Fresnel lens having a facet formed on a substrate that includes an optical material. In some examples, the optical construction may include one or more reflectors, such as a mirror and / or a reflector.

[0158] In some examples, components of the optical construction can include one or more optical materials. For example, the optical material can include glass or optical plastic. The optical material can be substantially transmissive over part or all of the visible spectrum. In some examples, an optical component including a substantially transmissive material can have an optical transmittance greater than 0.9 over some or all of the visible spectrum.

[0159] In some examples, the substrate (e.g., a substrate for a reflector), optical material and / or layer (e.g., a layer of an optical component) may include one or more of the following: an oxide (e.g., silicon dioxide, aluminum oxide, titanium dioxide, other metal oxides (such as transition metal oxides), or other non-metal oxides); a semiconductor (e.g., an intrinsic semiconductor or a doped semiconductor (such as silicon (e.g., amorphous silicon or crystalline silicon), carbon, germanium), a phosphide semiconductor, or a chalcogenide semiconductor, etc.); a nitride (e.g., silicon nitride, boron nitride, or other nitrides including nitride semiconductors); a carbide (e.g., silicon carbide), an oxynitride (e.g., silicon oxynitride); a polymer; a glass (e.g., a silicate glass (such as borosilicate glass), a fluoride glass, or other glass); or other material.

[0160] In some examples, a device may include a display (e.g., a display panel) and a folded optical lens, which optionally has a segmented reflectivity, as described herein. Light incident on the folded optical lens from the display panel may be circularly polarized. The display may be an emissive display or may include a backlight. The emissive display may include an array of light emitting diodes (LEDs), such as an array of organic light emitting diodes (OLEDs). In some examples, the LED array may include an array of micro-LEDs (microLEDs), and the spacing between each LED may be approximately or less than 100 microns (e.g., approximately or less than 50 microns, approximately or less than 20 microns, approximately or less than 10 microns, approximately or less than 5 microns, approximately or less than 2 microns, approximately or less than 1 micron, or other spacing values).

[0161] In some examples, the display may emit polarized light, such as linear polarized light or circular polarized light. In some examples, the display may emit linear polarized light, and the optical retarder may convert the linear polarization to an orthogonal linear polarization. In some examples, the combination of the optical retarder and the linear reflective polarizer may be replaced by an alternative configuration, such as a circular polarization reflective polarizer that may include a cholesteric liquid crystal reflective polarizer.

[0162] In some examples, the reflective polarizer can include a cholesteric liquid crystal, such as a polymer cholesteric liquid crystal, such as a cross-linked polymer cholesteric liquid crystal. In some examples, the reflective polarizer can include a birefringent multilayer reflective polarizer combined with a quarter-wave retarder placed between the reflective polarizer and a second reflector (e.g., a beam splitter or other reflective polarizer).

[0163] In some examples, the display may include a transmissive display (such as a liquid crystal display) and a light source (such as a backlight). In some examples, the display may include a spatial light modulator and a light source. An example spatial light modulator may include a reflective switchable liquid crystal array or a transmissive switchable liquid crystal array.

[0164] In some examples, an apparatus may include a display configured to provide polarized light (such as circularly polarized light). The display may include an emissive display (e.g., a light emitting display) or a display used in conjunction with a backlight (e.g., a liquid crystal display).

[0165] In some examples, the display light from the display incident on the beam splitter lens is circularly polarized. The display may include an emissive display (such as a light emitting diode display) or a light absorbing panel (such as a liquid crystal panel) combined with a backlight. The emissive display may include at least one LED array, such as an organic LED (OLED) array. The LED array may include a micro-LED array. The LED array may include a plurality of LEDs having a spacing of less than about 100 microns (e.g., about 50 microns, about 20 microns, about 10 microns, about 5 microns, about 2 microns, or about 1 micron, etc.).

[0166] In some examples, a display can include a spatial light modulator and a light source (e.g., a backlight). The spatial light modulator can include a reflective switchable liquid crystal array or a transmissive switchable liquid crystal array. In some examples, the light source (e.g., a backlight) can have and / or allow spatial variations in illumination intensity on the display. In some examples, the light source can include a scanning source, such as a scanning laser. In some examples, the light source can include an arrangement of light emitting elements, such as an array of light emitting elements. The array of light emitting elements can include an array of mini LED (miniLED) emitting elements and / or an array of micro LED emitting elements.

[0167] In some examples, a display may include one or more waveguide displays. A waveguide display may include a multicolor display, or an arrangement of multiple monochrome displays. A waveguide display may be configured to project display light from one or more waveguides into an optical construction configured to form an image of at least a portion of the display at an eye zone.

[0168] In some examples, the display brightness can be spatially varied to increase the brightness uniformity of the imaging display by at least, for example, about 10%, for example, about 20%, for example, about 30%, for example, about 40%, or some other value. The display illumination variation can be dynamically controlled by, for example, a controller. In some examples, the dynamic illumination variation can be adjusted by the controller receiving eye tracking signals provided by an eye tracking system.

[0169] In some examples, the display can have a spatially adjustable brightness (e.g., spatial variation of illumination intensity). In some examples, the adjustable brightness can be achieved by spatially varying the brightness of the emissive display or the brightness of the backlight. The display brightness and / or any spatial variation can be adjusted, for example, by a control circuit. In some examples, the light source can include a scannable light source, such as a laser. In some examples, the light source can include an array of light sources, such as an LED backlight. For example, the array of light sources can include a mini LED array or a micro LED array. The display illumination can be spatially varied to increase the brightness uniformity of the imaging display by at least about 10% (e.g., about 20%, about 30%, about 40%, or other values). The spatial variation of the illumination from the backlight can be dynamically adjusted, and the dynamic adjustment can be controlled by an eye tracking system.

[0170] In some examples, the apparatus can include one or more actuators. For example, one or more actuators can be used to position the reflective polarizer relative to the Fresnel lens (e.g., to place a portion of the reflective polarizer in registration with a facet of the Fresnel lens) and / or to push the reflective polarizer against the Fresnel lens (e.g., using an elastomeric element).

[0171] Example actuators may include piezoelectric actuators, which may include piezoelectric materials such as crystals or ceramic materials. Example actuators may include actuator materials such as one or more of the following: lead magnesium niobium oxide, lead zinc niobium oxide, lead scandium tantalum oxide, lead lanthanum zirconium titanium oxide, barium titanium zirconium oxide, barium titanium tin oxide, lead magnesium titanium oxide, lead scandium niobium oxide, lead indium niobium oxide, lead indium tantalum oxide, lead iron niobium oxide, lead iron tantalum oxide, lead zinc tantalum oxide, lead iron tungsten oxide, barium strontium titanium oxide, barium zirconium oxide, bismuth magnesium niobium oxide, bismuth magnesium tantalum oxide, bismuth zinc niobium oxide, bismuth zinc tantalum oxide, lead ytterbium niobium oxide, lead ytterbium tantalum oxide, strontium titanium oxide, bismuth titanium oxide, calcium titanium oxide, lead magnesium niobium titanium oxide, Lead magnesium niobium titanium zirconium oxide, lead zinc niobium titanium oxide, lead zinc niobium titanium zirconium oxide, and mixtures of any of the foregoing materials with any of the foregoing materials and / or conventional ferroelectrics (these conventional ferroelectrics include: lead titanium oxide, lead zirconium titanium oxide, barium titanium oxide, bismuth iron oxide, sodium bismuth titanium oxide, lithium tantalum oxide, sodium potassium niobium oxide, and lithium niobium oxide), and also: lead titanate, lead zirconate, lead zirconate titanate, lead magnesium niobate, lead magnesium niobate-lead titanate, lead zinc niobate, lead zinc niobate-lead titanate, lead magnesium tantalate, lead indium niobate, lead indium tantalate, barium titanate, lithium niobate, potassium niobate, potassium sodium niobate, bismuth sodium titanate, or bismuth ferrite. One or more of the various example actuator materials listed above may also be used as an optical material, layer (e.g., a layer of an optical component) or substrate material (e.g., a substrate of a beam splitter). In some examples, the actuator can be configured to adjust the position and / or configuration of an optical element (such as a lens).

[0172] An example apparatus (such as a head mounted device) may include a Fresnel lens assembly including a Fresnel lens and a reflective polarizer. The example reflective polarizer may be configured to reflect light of one polarization and transmit light of another polarization. For example, the example reflective polarizer may reflect circularly polarized light of one chirality and may transmit circularly polarized light of another chirality. The example reflective polarizer may reflect one linear polarization direction and transmit an orthogonal linear polarization direction. The example apparatus may include a display, and the display may be configured to emit polarized light. In some examples, the apparatus may be an augmented reality and / or virtual reality (AR / VR) head mounted viewer.

[0173] In some examples, a Fresnel lens assembly includes at least one Fresnel lens, and the Fresnel lens assembly is configured to reflect light of a first polarization and transmit light of a second polarization. The Fresnel lens assembly can include a reflective polarizer layer disposed on a facet of a structured surface of the Fresnel lens. In some examples, a structured optical element includes a substrate having at least two adjacent facets separated by a step (sometimes referred to as a facet), wherein the facets have facet surfaces, wherein the reflective polarizer layer is adjacent to and conforms to at least a portion of the facet surface of at least one of the plurality of facets.

[0174] In some examples, the Fresnel lens can have a reflective polarizer formed as a cladding on the facet of the lens. The cladding can include a multilayer optical film, a cholesteric liquid crystal, or an anisotropic conductor. The facets of the Fresnel lens and the polarizer can be embedded in an optically transparent filling polymer. For example, the filling layer can be formed to be supported by an assembly including the Fresnel lens and the polarizer. The filling layer can include an optically transparent polymer. The filling layer can have a structured surface complementary to the Fresnel lens and any other cladding layer disposed on the Fresnel lens, and the filling layer includes a second surface that can be generally smooth (e.g., planar, concave, or convex), or in some examples, the second surface can be faceted to provide additional optical power (e.g., using a second Fresnel lens formed in the filling layer). The refractive index and optical dispersion of the Fresnel lens material and the filling polymer can be selected to reduce chromatic aberration (e.g., color fringing in an image). Preferably, the optical material has low birefringence (e.g., optical retardation less than λ / 4). The Fresnel lens and / or the filling polymer may include a silicone polymer such as polydimethylsiloxane (PDMS), cyclic olefin polymer (COP), cyclic olefin copolymer (COC), polyacrylate, polyurethane, or polycarbonate. For example, a PDMS Fresnel lens may be supported on a rigid substrate such as glass. Vapor deposition of the coating may result in unwanted deposition on the facades between the facets. An elastic substrate may be used to selectively position a suitably segmented coating on the facets of the Fresnel lens. A reflective polarizer supported by a Fresnel lens may be used in an augmented reality and / or virtual reality (AR / VR) system. Other components may include a display and a beam splitter. In some examples, an AR / VR system may include a beam splitter supported by a Fresnel lens, and the lens may be optimized separately. The Fresnel lens may be concave, convex, or may have a complex optical profile such as a free surface. Wavelength-dependent properties may be adjusted by, for example, adjusting the multilayer film construction. Applications may also include, for example, IR suppression in imaging systems, display systems, or photovoltaic systems.

[0175] In some examples, an apparatus may include a display and an optical construction configured to provide an image of the display, for example, in a head-mounted device. The optical construction may include a Fresnel lens assembly including a Fresnel lens and a reflective polarizer. The Fresnel lens may have a structured surface including a plurality of facets and may have steps between pairs of adjacent facets. The reflective polarizer may include a plurality of reflective polarizer portions, wherein each reflective polarizer portion conforms to a corresponding facet of the Fresnel lens. The reflective polarizer may be configured to reflect incident light of a first polarization and transmit incident light of a second polarization. When a user wears the apparatus, the optical construction may form an image of the display viewable by the user. The examples also include other devices, methods, systems, and computer-readable media.

[0176] Example Embodiments

[0177] Example 1: An example device may include a Fresnel lens assembly, wherein the Fresnel lens assembly includes: a Fresnel lens; and a reflective polarizer, wherein the Fresnel lens has a structured surface, the structured surface including a plurality of facets; the reflective polarizer includes a plurality of reflective polarizer portions; each of the plurality of reflective polarizer portions conforms to a corresponding facet of the plurality of facets; the reflective polarizer is configured to reflect light of a first polarization incident on the reflective polarizer; and the reflective polarizer is configured to transmit light of a second polarization incident on the reflective polarizer.

[0178] Example 2. The apparatus of Example 1, wherein the first polarization is circularly polarized light of a first handedness; the second polarization is circularly polarized light of a second handedness; and the reflective polarizer comprises a chiral solid.

[0179] Example 3. A device according to any one of Examples 1 or 2, wherein the first polarization is linearly polarized light in a first direction; the second polarization is linearly polarized light in a second direction; and the first direction is orthogonal to the second direction.

[0180] Example 4. A device according to any of Examples 1 to 3, wherein the reflective polarizer comprises an optical multilayer film.

[0181] Example 5. A device according to any one of Examples 1 to 4, wherein the multiple facets include a central facet; and the reflective polarizer includes a central portion that conforms to the central facet.

[0182] Example 6. An apparatus according to any one of Examples 1 to 5, wherein the multiple facets also include an annular facet, the reflective polarizer includes an annular portion that conforms to the annular facet; the central facet is a circular facet, and the annular facet surrounds the central facet and is concentric with the central facet.

[0183] Example 7. A device according to any one of Examples 1 to 6, wherein the structured surface of the Fresnel lens includes steps located between adjacent facets among the multiple facets; and the reflective polarizer does not cover the steps of the structured surface.

[0184] Example 8. A device according to any of Examples 1 to 7, wherein each of the plurality of reflective polarizer portions is attached to the corresponding facet of the plurality of facets using an adhesive layer.

[0185] Example 9. A device according to any one of Examples 1 to 8, wherein the size of each of the multiple reflective polarizer portions is set to match the corresponding cut facet of the multiple cut faces.

[0186] Example 10. A device according to any one of Examples 1 to 9, wherein the Fresnel lens assembly further comprises a filling polymer layer disposed above the reflective polarizer; and the filling polymer layer comprises an optically transparent polymer.

[0187] Example 11. A device according to any one of Examples 1 to 10, wherein the reflective polarizer comprises: a first surface that conforms to the structured surface of the Fresnel lens; and a second surface that includes an external cut facet and an external step.

[0188] Example 12. An apparatus according to any one of Examples 1 to 11, wherein the apparatus further comprises: a display; and an optical structure configured to provide an image of the display, wherein: the optical structure comprises the Fresnel lens assembly; the apparatus comprises a head-mounted device; and when a user of the apparatus wears the head-mounted device, the user is able to see the image of the display.

[0189] Example 13. An apparatus according to Example 12, wherein the apparatus comprises an augmented reality device or a virtual reality device.

[0190] Example 14. A device according to Example 12 or 13, wherein the optical structure includes a folded optical structure; and when light from the display passes from the display through the optical structure to form the image of the display at the user's eye, the light is reflected by the Fresnel lens assembly and transmitted through the Fresnel lens assembly.

[0191] Example 15. A device according to any one of Examples 12 to 14, wherein the optical structure also includes a beam splitter lens and an optical delay.

[0192] Example 16. An apparatus according to any of Examples 12 to 15, wherein the display is configured to emit light having circular polarization.

[0193] Example 17. A method includes: forming a reflective polarizer on a substrate; patterning the reflective polarizer to form a reflective polarizer portion, the size of the reflective polarizer portion being set to match the corresponding cut surface of the Fresnel lens; and applying the reflective polarizer portion to the corresponding cut surface of the Fresnel lens by pushing the reflective polarizer portion against the corresponding cut surface of the Fresnel lens using a force applied to the substrate.

[0194] Example 18. The method of Example 17, further comprising forming a fill layer that conforms to the reflective polarizer portion, wherein the fill layer comprises an optically transparent polymer.

[0195] Example 19. The method of any one of Examples 17 or 18, wherein forming the reflective polarizer on the substrate includes forming the reflective polarizer on an elastomeric element.

[0196] Example 20. A method according to any one of Examples 17 to 19, further comprising removing the substrate so that the reflective polarizer portion remains bonded to a corresponding portion of the Fresnel lens, wherein the reflective polarizer is adhered to the substrate with a UV reversible adhesive or a thermal reversible adhesive; and removing the substrate comprises UV irradiation or thermal stripping.

[0197] Embodiments of the present disclosure may include various types of artificial reality systems, or be implemented in combination with various types of artificial reality systems. Artificial reality is a form of reality that has been adjusted in some way before being presented to a user, and artificial reality may include, for example, virtual reality, augmented reality, mixed reality, hybrid reality, or some combination and / or derivative thereof. Artificial reality content may include fully computer-generated content or computer-generated content combined with collected (e.g., real-world) content. Artificial reality content may include video, audio, tactile feedback, or some combination thereof, any of which may be presented in a single channel or multiple channels (e.g., stereoscopic video that produces a three-dimensional (3D) effect to the viewer). In addition, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, which are used, for example, to create content in artificial reality and / or otherwise used in artificial reality (e.g., performing activities in artificial reality).

[0198] Artificial reality systems may be implemented in a variety of different form factors and configurations. Some artificial reality systems may be designed to operate without a near-eye display (NED). Other artificial reality systems may include a NED (such as, for example, Fig.21 The NED also provides visibility into the real world or visually immerses the user in an artificial reality (such as, for example, Fig. 22 2200). While some artificial reality devices may be stand-alone systems, other artificial reality devices may communicate and / or cooperate with external devices to provide an artificial reality experience to a user. Examples of such external devices include handheld controllers, mobile devices, desktop computers, devices worn by a user, devices worn by one or more other users, and / or any other suitable external system.

[0199] Go to Fig.21 , the augmented reality system 2100 may include an eye-mounted device 2102 having a frame 2110 configured to hold a left display device 2115(A) and a right display device 2115(B) in front of the user's eyes. Display devices 2115(A) and 2115(B) may function together or independently to present an image or a series of images to the user. Although the augmented reality system 2100 includes two displays, embodiments of the present disclosure may be implemented in an augmented reality system having a single NED or more than two NEDs.

[0200] In some embodiments, the augmented reality system 2100 may include one or more sensors, such as sensor 2140. Sensor 2140 may generate measurement signals in response to the movement of the augmented reality system 2100 and may be located on substantially any portion of the frame 2110. Sensor 2140 may represent one or more of a variety of different sensing mechanisms, such as a position sensor, an inertial measurement unit (IMU), a depth camera assembly, a structured light emitter and / or detector, or any combination thereof. In some embodiments, the augmented reality system 2100 may or may not include sensor 2140, or may include more than one sensor. In embodiments where sensor 2140 includes an IMU, the IMU may generate calibration data based on the measurement signals from sensor 2140. Examples of sensor 2140 may include, but are not limited to, accelerometers, gyroscopes, magnetometers, other suitable types of sensors that detect movement, sensors for error calibration of IMUs, or some combination thereof.

[0201] In some examples, the augmented reality system 2100 may also include a microphone array having a plurality of acoustic transducers 2120 (A) to 2120 (J), which are collectively referred to as acoustic transducers 2120. The acoustic transducers 2120 may represent transducers that detect changes in air pressure caused by sound waves. Each acoustic transducer 2120 may be configured to detect sound and convert the detected sound into an electronic format (e.g., an analog mode or a digital format). Fig.21 The microphone array in can include, for example, ten acoustic transducers: acoustic transducers 2120(A) and 2120(B) that can be designed to be placed in corresponding ears of a user; acoustic transducers 2120(C), 2120(D), 2120(E), 2120(F), 2120(G) and 2120(H) that can be positioned at different locations on the frame 2110; and / or acoustic transducers 2120(I) and 2120(J) that can be positioned on the corresponding neckband 2105.

[0202] In some embodiments, one or more of the acoustic transducers 2120(A) to 2120(J) can be used as an output transducer (e.g., a speaker). For example, the acoustic transducer 2120(A) and / or the acoustic transducer 2120(B) can be an earbud or any other suitable type of headphone or speaker.

[0203] The configuration of the acoustic transducer 2120 of the microphone array may vary. Fig.21 10 acoustic transducers 2120 are shown in the figure, but the number of acoustic transducers 2120 can be more or less than ten. In some embodiments, the use of a greater number of acoustic transducers 2120 can increase the amount of audio information collected and / or improve the sensitivity and accuracy of the audio information. In contrast, the use of a smaller number of acoustic transducers 2120 can reduce the computing power required for the associated controller 2150 to process the collected audio information. In addition, the position of each acoustic transducer 2120 of the microphone array can vary. For example, the position of the acoustic transducer 2120 can include a defined position on the user, a defined coordinate on the frame 2110, an orientation associated with each acoustic transducer 2120, or some combination thereof.

[0204] The acoustic transducers 2120(A) and 2120(B) can be positioned on different parts of the user's ear, such as behind the ear wing, behind the tragus, and / or in the auricle or ear cavity. Alternatively, in addition to the acoustic transducer 2120 in the ear canal, additional acoustic transducers 2120 can be present on or around the ear. Having the acoustic transducer 2120 located near the user's ear canal enables the microphone array to collect information about how sound reaches the ear canal. By positioning at least two of the multiple acoustic transducers 2120 on both sides of the user's head (e.g., as binaural microphones), the augmented reality system 2100 can simulate binaural hearing and capture a 3D stereo field around the user's head. In some embodiments, acoustic transducers 2120(A) and 2120(B) may be connected to augmented reality system 2100 via wired connection 2130, while in other embodiments, acoustic transducers 2120(A) and 2120(B) may be connected to augmented reality system 2100 via a wireless connection (e.g., a Bluetooth connection). In other embodiments, acoustic transducers 2120(A) and 2120(B) may not be used in conjunction with augmented reality system 2100 at all.

[0205] The acoustic transducers 2120 on the frame 2110 can be positioned in a variety of different ways, including along the length of the temples, across the bridge, above or below the display device 2115(A) and the display device 2115(B), or some combination thereof. The acoustic transducers 2120 can also be oriented so that the microphone array can detect sounds in a wide range of directions around the user wearing the augmented reality system 2100. In some embodiments, an optimization process can be performed during the manufacture of the augmented reality system 2100 to determine the relative positioning of each acoustic transducer 2120 in the microphone array.

[0206] In some examples, the augmented reality system 2100 may include or may be connected to an external device (e.g., a paired device), such as a neckband 2105. The neckband 2105 generally represents any type or form of paired device. Therefore, the discussion of the neckband 2105 herein may also be applied to various other paired devices, such as a charging case, a smart watch, a smartphone, a wristband, other wearable devices, a handheld controller, a tablet computer, a portable computer, other external computing devices, etc.

[0207] As shown, the neckband 2105 can be coupled to the eye-mounted device 2102 via one or more connectors. These connectors can be wired or wireless and can include electrical and / or non-electrical components (e.g., structural components). In some cases, the eye-mounted device 2102 and the neckband 2105 can operate independently without any wired or wireless connection between them. Although Fig.21 Components of the eye-mounted device 2102 and components of the neckband 2105 are shown at example locations on the eye-mounted device 2102 and the neckband 2105, but these components can be located at other locations on the eye-mounted device 2102 and / or the neckband 2105 and / or distributed on the eye-mounted device and / or the neckband 2105 in different ways. In some embodiments, components of the eye-mounted device 2102 and the neckband 2105 can be located on one or more additional peripheral devices paired with the eye-mounted device 2102, on the neckband 2105, or some combination thereof.

[0208] Pairing an external device, such as a neckband 2105, with an augmented reality eye-mounted device may enable the eye-mounted device to achieve the form factor of a pair of glasses and still provide sufficient battery and computing power for expanded capabilities. Some or all of the battery power, computing resources, and / or additional features of the augmented reality system 2100 may be provided by a paired device or shared between the paired device and the eye-mounted device, thereby reducing the weight, thermal distribution, and form factor of the eye-mounted device overall while still retaining the desired functionality. For example, the neckband 2105 may allow components that would otherwise be included on the eye-mounted device to be included in the neckband 2105 because a user may carry a heavier weight load on their shoulders than a user may carry on their head. The neckband 2105 may also have a larger surface area through which to diffuse and dissipate heat into the surrounding environment. Thus, the neckband 2105 may allow for greater battery capacity and computing power than would otherwise be possible on a standalone eye-mounted device. Because the weight carried in the neckband 2105 can be less invasive to the user than the weight carried in the eye-mounted device 2102, the user can tolerate wearing a lighter eye-mounted device and carrying or wearing a paired device for a longer period of time than the user can tolerate wearing a heavy stand-alone eye-mounted device, thereby enabling the user to more fully integrate the artificial reality environment into their daily activities.

[0209] The neckband 2105 can be communicatively coupled to the eye-mounted device 2102 and / or other devices. These other devices can provide certain functions (e.g., tracking, positioning, depth map construction, processing, storage, etc.) for the augmented reality system 2100. Fig.21 In an embodiment of the present invention, the neckband 2105 may include two acoustic transducers (e.g., acoustic transducers 2120(I) and 2120(J)), which are part of the microphone array (or potentially form their own microphone subarray). The neckband 2105 may also include a controller 2125 and a power supply 2135.

[0210] The acoustic transducers 2120(I) and 2120(J) of the neckband 2105 may be configured to detect sound and convert the detected sound into an electronic format (analog or digital). Fig.21 In an embodiment of the present invention, the acoustic transducer 2120(I) and the acoustic transducer 2120(J) can be positioned on the neckband 2105, thereby increasing the distance between the acoustic transducer 2120(I) and the acoustic transducer 2120(J) of the neckband and other acoustic transducers 2120 positioned on the eye-mounted device 2102. In some cases, increasing the distance between the acoustic transducers 2120 of the microphone array can improve the accuracy of beamforming performed via the microphone array. For example, if a sound is detected by the acoustic transducer 2120(C) and the acoustic transducer 2120(D), and the distance between the acoustic transducer 2120(C) and the acoustic transducer 2120(D) is, for example, greater than the distance between the acoustic transducer 2120(D) and the acoustic transducer 2120(E), the determined source location of the detected sound can be more accurate than when the sound is detected by the acoustic transducers 2120(D) and 2120(E).

[0211] The controller 2125 of the neckband 2105 can process information generated by multiple sensors on the neckband 2105 and / or the augmented reality system 2100. For example, the controller 2125 can process information from the microphone array that describes the sound detected by the microphone array. For each detected sound, the controller 2125 can perform an estimate of the direction of arrival (Direction-of-Arrival, DOA) to estimate the direction from which the detected sound arrives at the microphone array. When the microphone array detects a sound, the controller 2125 can fill the audio data set with this information. In an embodiment where the augmented reality system 2100 includes an inertial measurement unit, the controller 2125 can calculate all inertial and spatial operations based on the IMU located on the eye-mounted device 2102. The connector can transmit information between the augmented reality system 2100 and the neckband 2105 and between the augmented reality system 2100 and the controller 2125. The information can be in the form of optical data, electronic data, wireless data, or any other transmittable data form. Moving the processing of information generated by the augmented reality system 2100 to the neck strap 2105 can reduce the weight and heat of the eye-mounted device 2102, making it more comfortable for the user.

[0212] The power supply 2135 in the neckband 2105 can provide power to the eye-mounted device 2102 and / or the neckband 2105. The power supply 2135 can include, but is not limited to, lithium-ion batteries, lithium polymer batteries, disposable lithium batteries, alkaline batteries, or any other form of power storage device. In some cases, the power supply 2135 can be a wired power supply. Including the power supply 2135 on the neckband 235 instead of on the eye-mounted device 2102 can help better distribute the weight and heat generated by the power supply 2135.

[0213] As noted, some artificial reality systems can substantially replace one or more of a user's multiple sensory perceptions of the real world with a virtual experience, rather than blending the artificial reality with the real reality. An example of this type of system is a head-mounted display system that largely or completely covers the user's field of view, such as Fig. 22 2200 in the virtual reality system. The virtual reality system 2200 may include a front rigid body 2202 and a band 2204 shaped to fit around the user's head. The virtual reality system 2200 may also include output audio converters 2206 (A) and 2206 (B). In addition, although in Fig. 22 Not shown, but the front rigid body 2202 may include one or more electronic components, including one or more electronic displays, one or more inertial measurement units (IMUs), one or more tracking transmitters or detectors, and / or any other suitable device or system for creating an artificial reality experience.

[0214] Artificial reality systems may include various types of visual feedback mechanisms. For example, the display devices in the augmented reality system 2100 and / or the virtual reality system 2200 may include one or more liquid crystal displays (LCD), light emitting diode (LED) displays, microLED (microLED) displays, organic LED (Organic Light Emitting Diode, OLED) displays, digital light projection (Digital Light Project, DLP) microdisplays, liquid crystal on silicon (Liquid Crystal on Silicon, LCoS) microdisplays, and / or any other suitable type of display screen. These artificial reality systems may include a single display screen for both eyes, or a display screen may be provided for each eye, which may allow additional flexibility for zoom adjustment or correction of the user's refractive error. Some of these artificial reality systems may also include an optical subsystem having one or more lenses (e.g., concave or convex lenses, Fresnel lenses, adjustable liquid lenses, etc.), through which the user can view the display screen. These optical subsystems can be used for a variety of purposes, including collimating light (e.g., making an object appear to be at a greater distance than it is physically located), magnifying light (e.g., making an object appear larger than its actual size), and / or relaying light (e.g., relaying light to a viewer's eye). These optical subsystems can be used in non-pupil-forming architectures (e.g., a single lens configuration that directly collimates light but causes so-called pincushion distortion) and / or pupil-forming architectures (e.g., a multi-lens configuration that produces so-called barrel distortion to eliminate pincushion distortion).

[0215] In addition to or in lieu of using a display screen, some of the artificial reality systems described herein may include one or more projection systems. For example, a display device in the augmented reality system 700 and / or a display device in the virtual reality system 800 may include a micro-LED projector that projects light (using, for example, a waveguide) into the display device, such as a transparent combiner lens that allows ambient light to pass through. The display device may refract the projected light toward the user's pupil, and may enable the user to view both the artificial reality content and the real world simultaneously. The display device may achieve this using any of a variety of different optical components, including waveguide components (e.g., holographic waveguide elements, planar waveguide elements, diffractive waveguide elements, polarizing waveguide elements, and / or reflective waveguide elements), light manipulation surfaces and elements (such as diffractive elements and gratings, reflective elements and gratings, and refractive elements and gratings), coupling elements, and the like. The artificial reality system may also be configured with any other suitable type or form of image projection system, such as a retinal projector for a virtual retinal display.

[0216] The artificial reality systems described herein may also include various types of computer vision components and subsystems. For example, the augmented reality system 2100 and / or the virtual reality system 2200 may include one or more optical sensors, such as a two-dimensional (2D) camera or a three-dimensional (3D) camera, a structured light emitter and detector, a time-of-flight depth sensor, a single-beam rangefinder or a scanning laser rangefinder, a 3D laser radar (LiDAR) sensor, and / or any other suitable type or form of optical sensor. The artificial reality system may process data from one or more of these sensors to identify the user's location, map the real world, provide content about the real-world environment to the user, and / or perform various other functions.

[0217] The artificial reality system described herein may also include one or more input audio converters and / or output audio converters. The output audio converter may include a voice coil speaker, a ribbon speaker, an electrostatic speaker, a piezoelectric speaker, a bone conduction converter, a cartilage conduction converter, an ear tragus vibration converter, and / or any other suitable type or form of audio converter. Similarly, the input audio converter may include a condenser microphone, a dynamic microphone, a ribbon microphone, and / or any other type or form of input converter. In some embodiments, a single converter may be used for both audio input and audio output.

[0218] In some embodiments, the artificial reality systems described herein may also include tactile (i.e., haptic) feedback systems that can be incorporated into headwear, gloves, clothing, handheld controllers, environmental devices (e.g., chairs, floor mats, etc.), and / or any other type of device or system. The tactile feedback system can provide various types of skin feedback, including vibration, force, traction, texture, and / or temperature. The tactile feedback system can also provide various types of kinesthetic feedback, such as motion and compliance. Tactile feedback can be implemented using motors, piezoelectric actuators, fluid systems, and / or various other types of feedback mechanisms. The tactile feedback system can be implemented independently of other artificial reality devices, within other artificial reality devices, and / or in combination with other artificial reality devices.

[0219] By providing tactile perception, auditory content, and / or visual content, artificial reality systems can create complete virtual experiences or enhance users' real-world experiences in various contexts and environments. For example, artificial reality systems can assist or expand users' perception, memory, or cognition in a specific environment. Some systems can enhance users' interactions with other people in the real world, or can enable more immersive interactions with other people in the virtual world. Artificial reality systems can also be used for educational purposes (e.g., for teaching or training in schools, hospitals, government organizations, military organizations, commercial enterprises, etc.), entertainment purposes (e.g., for playing video games, listening to music, watching video content, etc.), and / or for accessibility purposes (e.g., as hearing aids, visual aids, etc.). The embodiments disclosed herein can implement or enhance users' artificial reality experiences in one or more of these contexts and environments and / or in other contexts and environments.

[0220] As described above, the computing devices and systems described and / or illustrated herein broadly represent any type or form of computing device or system capable of executing computer-readable instructions (such as those contained in the modules described herein). In its most basic configuration, these computing devices may each include at least one storage device and at least one physical processor.

[0221] In some examples, the term "memory device" generally refers to any type or form of volatile or non-volatile storage device or medium capable of storing data and / or computer-readable instructions. In one example, a memory device can store, load and / or maintain one or more of these modules described herein. Examples of memory devices include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, hard disk drive (HDD), solid-state drive (SSD), optical disk drive, cache memory, one or more of them or a combination thereof, or any other suitable storage memory.

[0222] In some examples, the term "physical processor" generally refers to a hardware-implemented processing unit of any type or form that can interpret and / or execute computer-readable instructions. In one example, a physical processor can access and / or modify one or more modules stored in the above-mentioned memory device. Examples of physical processors include, but are not limited to, a microprocessor, a microcontroller, a central processing unit (CPU), a field programmable gate array (FPGA) implementing a soft-core processor, an application-specific integrated circuit (ASIC), a portion of one or more of them, a variation or combination of one or more of them, or any other suitable physical processor.

[0223] Although shown as separate elements, the modules described and / or shown herein can represent parts of a single module or application. In addition, in certain embodiments, one or more modules in these modules can represent one or more software applications or programs, which can make a computing device perform one or more tasks when executed by a computing device. For example, one or more modules in these modules described and / or shown herein can represent modules stored and configured to run on one or more computing devices or systems in a plurality of computing devices or systems described and / or shown herein. One or more modules in these modules can also represent all or part of one or more special-purpose computers configured to perform one or more tasks.

[0224] In addition, one or more of the multiple modules described herein can convert data, physical devices, and / or representations of physical devices from one form to another. For example, one or more of the modules described herein can receive data to be converted (e.g., eye tracking sensor data), convert the data (e.g., to one or more of gaze direction, observed object, or other visual parameters), output the result of the conversion to perform a function (e.g., modify an augmented reality environment, modify a real environment, modify operating parameters of a real device or a virtual device, provide a control signal to a device such as an electronic device, a vehicle, or other device), use the result of the conversion to perform a function, and store the result of the conversion to perform a function (e.g., in a storage device). Additionally or alternatively, one or more of the modules described herein can convert a processor, volatile memory, non-volatile memory, and / or any other part of a physical computing device from one form to another by executing on a computing device, storing data on a computing device, and / or otherwise interacting with a computing device.

[0225] In some embodiments, the term "computer-readable medium" generally refers to any form of device, carrier, or medium capable of storing or carrying computer-readable instructions. Examples of computer-readable media include, but are not limited to, transmission-type media (such as carrier waves) and non-transitory media (such as magnetic storage media (e.g., hard drives, tape drives, and floppy disks), optical storage media (e.g., compact discs (CDs), digital video discs (DVDs), and Blu-ray discs (BLU-RAY disks)), electronic storage media (e.g., solid-state drives and flash memory media), and other distribution systems).

[0226] The process parameters and order of steps described and / or illustrated herein are given as examples only and may be changed as desired. For example, although the steps illustrated and / or described herein may be shown or discussed in a particular order, the steps do not necessarily need to be performed in the order shown or discussed. The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein, or include additional steps in addition to those disclosed.

[0227] The previous description has been provided to enable others skilled in the art to best utilize the various aspects of the exemplary embodiments disclosed herein. This exemplary description is not intended to be exhaustive or limited to any precise form disclosed. Many modifications and variations are possible without departing from the scope of the present disclosure. The embodiments disclosed herein may be considered to be illustrative and not restrictive in all respects. In determining the scope of the present disclosure, reference may be made to any of the attached claims and their equivalents.

[0228] Unless otherwise indicated, the terms "connected to" and "coupled to" (and their derivatives) used in the specification and / or claims should be interpreted as allowing both direct and indirect (i.e., via other elements or components) connections. In addition, the terms "a" or "an", as used in the specification and / or claims, are interpreted to mean "at least one of..." Finally, for ease of use, as used in the specification and / or claims, the terms "including" and "having" (and their derivatives) are interchangeable with the word "comprising" and have the same meaning.

Claims

1. A device comprising a Fresnel lens assembly, wherein: The Fresnel lens assembly comprises: Fresnel lenses; and A reflective polarizer, wherein: The Fresnel lens has a structured surface, and the structured surface includes a plurality of facets; The reflective polarizer includes a plurality of reflective polarizer sections; each reflective polarizer portion of the plurality of reflective polarizer portions conforms to a corresponding facet of the plurality of facets; The reflective polarizer is configured to reflect light of a first polarization incident on the reflective polarizer; and The reflective polarizer is configured to transmit light of a second polarization incident on the reflective polarizer.

2. The device according to claim 1, wherein: The first polarization is circularly polarized light of a first handedness; The second polarization is circularly polarized light of a second handedness; and The reflective polarizer comprises a chiral solid.

3. The device according to claim 1 or 2, wherein: The first polarization is linearly polarized light in a first direction; The second polarization is linearly polarized light in a second direction; and The first direction is orthogonal to the second direction.

4. The device according to claim 1, 2 or 3, wherein: The reflective polarizer includes an optical multilayer film.

5. A device according to any one of the preceding claims, wherein: The plurality of slices include a central slice; and The reflective polarizer includes a central portion that conforms to the central cut plane; and preferably in: The plurality of cut surfaces also include an annular cut surface; The reflective polarizer includes an annular portion conforming to the annular cut surface; The central section is a circular section; and The annular section surrounds the central section and is concentric with the central section.

6. A device according to any one of the preceding claims, wherein: The structured surface of the Fresnel lens includes steps between adjacent facets of the plurality of facets; and The reflective polarizer does not cover the steps of the structured surface.

7. A device according to any one of the preceding claims, wherein: Each reflective polarizer portion of the plurality of reflective polarizer portions is attached to the corresponding facet of the plurality of facets using an adhesive layer.

8. A device according to any one of the preceding claims, wherein: Each of the plurality of reflective polarizer sections is sized to match the corresponding facet of the plurality of facets.

9. The device according to any one of the preceding claims, wherein: The Fresnel lens assembly further includes a filled polymer layer disposed above the reflective polarizer; and The filled polymer layer includes an optically clear polymer.

10. The device according to any one of the preceding claims, wherein: The reflective polarizer comprises: a first surface conforming to the structured surface of the Fresnel lens; and The second surface includes an external tangent surface and an external step.

11. The device according to any one of the preceding claims, wherein: The device also includes: Display; and an optical construction configured to provide an image for the display, wherein: the optical construction includes the Fresnel lens assembly; The apparatus comprises a head mounted device; and When a user of the apparatus wears the head mounted device, the user is able to see the image of the display; and preferably one or more of the following are present: i. wherein the device comprises an augmented reality device or a virtual reality device; ii. Among them: The optical construction comprises a folded optical construction; and when light from the display passes from the display through the optical construction to form the image of the display at the eye of the user, the light is reflected by and transmitted through the Fresnel lens assembly; iii. wherein the optical structure further comprises: beam splitter lens; and Optical retarders; iv. wherein the display is configured to emit light having circular polarization.

12. A method comprising: forming a reflective polarizer on a substrate; patterning the reflective polarizer to form a reflective polarizer portion sized to match a corresponding facet of the Fresnel lens; as well as The reflective polarizer portion is applied to the corresponding cut facet of the Fresnel lens by urging the reflective polarizer portion against the corresponding cut facet of the Fresnel lens using a force applied to the substrate.

13. The method of claim 12, further comprising forming a fill layer, the fill layer conforming to the reflective polarizer portion, wherein: The fill layer includes an optically clear polymer.

14. The method according to claim 12 or 13, wherein: Forming the reflective polarizer on the substrate includes forming the reflective polarizer on an elastomeric element.

15. The method of claim 12, 13 or 14, further comprising removing the substrate such that the reflective polarizer portion remains bonded to a corresponding portion of the Fresnel lens, wherein: adhering the reflective polarizer to the substrate with a UV reversible adhesive or a thermal reversible adhesive; and Removing the substrate includes UV irradiation or thermal stripping.

Images