Apparatus for adapting eyewear into augmented reality eyewear

Abstract

An apparatus comprising at least one transparent adhesive patch and an illumination device for adapting eyewear into augmented reality eyewear is disclosed. The at least one transparent adhesive patch has a metasurface thereon comprising reflective content and is configured for adhesion to a lens of the eyewear. The illumination device comprises a light source for illuminating the reflective content for projection onto a user's retina. The illumination device is provided with an attachment mechanism for attachment to the eyewear during use. In some embodiments, the illumination device is configured for side illumination of the metasurface. The metasurface may be fabricated with a phase distribution including an additional phase shift to address a uniform phase delay associated with off-axis illumination. The metasurface may be configured such that it does not impair the normal vision of the user when the light source is off.

Description

[0001] Apparatus for Adapting Eyewear into Augmented Reality Eyewear

[0002] TECHNICAL FIELD OF THE DISCLOSURE

[0003] The present disclosure relates to an apparatus for adapting eyewear into augmented reality eyewear.

[0004] BACKGROUND

[0005] Augmented reality is rapidly gaining prominence in the realm of interactive displays due to its distinctive capability of overlaying digital information onto the physical world.

[0006] Conventional technologies commonly utilized in augmented reality, such as waveguide-based displays, holographic displays, and optical see-through displays, are frequently linked to the presence of cumbersome optical components. Such systems, including commercially available headsets, are heavy and often prohibitively expensive.

[0007] Recent progress in augmented reality near-eye display systems includes incorporating grating waveguides, surface relief gratings, and metasurfaces into the system. Metasurfaces are a class of artificially designed nanostructures which can manipulate the electromagnetic properties of light in several ways. The smallest constituents of metasurfaces are called meta-atoms and they can be engineered to enable the control of scattered light at subwavelength scales. Metasurfaces are suitable for a wide range of applications such as the realisation of flat and compact lenses, the dynamic shaping of beams, the correction of optical aberrations, and the display of fullcolour images.

[0008] Disadvantages of existing systems include the fact that images are projected from a bulky projector which may require several lenses, beam splitters, and dichroic mirrors. Existing solutions require bespoke optics to deliver information to the wearer, which are expensive to produce.

[0009] It is an aim of at least one aspect of the present disclosure to provide an apparatus for adapting eyewear into augmented reality eyewear that ameliorates one or more of the described disadvantages. SUMMARY

[0010] In accordance with a first aspect of the disclosure there is provided an apparatus for adapting eyewear into augmented reality eyewear, comprising: at least one transparent adhesive patch having a metasurface thereon comprising reflective content, wherein the patch is configured for adhesion to a lens of the eyewear; and an illumination device comprising a light source for illuminating the reflective content for projection onto a user’s retina; wherein the illumination device is provided with an attachment mechanism for attachment to the eyewear during use.

[0011] Thus, embodiments of the invention provide an apparatus which can be attached to any eyewear, for example prescription glasses already belonging to a user. The apparatus does not require a projector or screen to overlay digital information on the user’s surroundings. When not in use, the apparatus can be switched off or removed from the eyewear. In either case, the user’s vision is not obscured by the transparent patch.

[0012] The illumination device may be configured for attachment to a temple (i.e. leg) of the eyewear.

[0013] The illumination device and / or metasurface may be positioned to accommodate different pupil distances of individual users.

[0014] The illumination device may be removable from the eyewear when not in use.

[0015] The illumination device may be configured for illumination of the metasurface in a direction that is not perpendicular to a (notional) plane of the metasurface.

[0016] The illumination device may be configured to emit light at an angle of illumination. The illumination device may be configured to emit light at an angle of illumination of approximately 20° to 80° or -20° to -80° in azimuth and / or at an angle of illumination of approximately 20° to 80° or -20° to -80° in elevation with respect to a longitudinal axis of the temple.

[0017] The angle of illumination may differ in azimuth and elevation.

[0018] The angle of illumination in elevation may be less than the angle of illumination in azimuth.

[0019] The angle of illumination may be 60° with respect to a longitudinal axis of the temple, when attached thereto. The side (or off-axis) illumination of the metasurface may facilitate distinction between zero-order diffracted light and the reflective content.

[0020] The illumination device may comprise a mirror configurable to direct light from the light source onto the metasurface during use.

[0021] The mirror may comprise an alignment mechanism configured to change a direction of light reflected from the mirror.

[0022] The illumination device may comprise a polarizer configured to polarise light from the light source prior to incidence on the metasurface during use.

[0023] The illumination device may comprise a quarter-wave plate.

[0024] The light source may comprise one or more of an LED, a laser and a fibre optic cable.

[0025] The light source may be configured to emit light at two or more wavelengths.

[0026] The metasurface may be fabricated with a phase distribution including an additional phase shift to address a uniform phase delay associated with off-axis illumination.

[0027] The metasurface may be configured (for example, by having small dimensions) such that it does not impair the normal vision of the user (i.e. a wearer of the eyewear) when the light source is off.

[0028] The metasurface may be circular, square, rectangular, triangular, or any other two-dimensional shape when in plan view.

[0029] The dimensions (e.g. diameter) of the metasurface may be of the order of tens of microns (e.g. 10 microns or more).

[0030] The dimensions (e.g. diameter) of the metasurface may be of the order of several mm.

[0031] The patch may be conformable to a curved surface of the lens.

[0032] The patch may be adhered to an inner surface of the lens, during use.

[0033] The attachment mechanism may comprise one or more of: a screw; a clip; a clasp; a clamp; a magnet; a snap-fit component; and a resilient component.

[0034] The alignment mechanism may comprise one or more of: a screw; a wheel; a spring; a motor; a lever; a hinge; a joint; a ball joint; and a switch.

[0035] The eyewear may be constituted by, for example, prescription glasses, safety glasses, toy glasses or sunglasses.

[0036] In accordance with a second aspect of the disclosure there is provided an illumination device for use in adapting eyewear into augmented reality eyewear, comprising: a light source for illuminating reflective content provided on a lens of the eyewear, for projection onto a user’s retina; and an attachment mechanism for attachment to the eyewear during use.

[0037] Thus, embodiments of the second aspect of the invention can be used to adapt eyewear into augmented reality eyewear without permanently altering the eyewear, with reduced weight and size when compared to traditional augmented reality headsets. The device may have reduced power requirements compared to a traditional augmented reality projector and screen. The reflective content is projected onto a user’s retina such that the rest of their surroundings may be viewed naturally.

[0038] In accordance with a third aspect of the disclosure there is provided a transparent adhesive patch configured for adhesion to a lens of an eyewear to adapt the eyewear into augmented reality eyewear, comprising: a metasurface thereon comprising reflective content.

[0039] Thus, embodiments of the third aspect of the invention do not impede the user’s vision when the light source is not in operation, and do not require any on-board power or computation as the metasurface itself comprises the reflective content and a screen is not required. The adhesive patch may be removed to revert adapted eyewear to its original state.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Embodiments will now be described by way of example only, and with reference to the accompanying drawings, of which:

[0042] Figure 1 shows a rear perspective view of an apparatus for adapting eyewear into augmented reality eyewear;

[0043] Figure 2A shows a rear perspective view of the illumination device attached to the eyewear using a first attachment mechanism;

[0044] Figure 2B shows a rear perspective view of the illumination device attached to the eyewear using a second attachment mechanism;

[0045] Figure 2C shows a rear perspective view of the illumination device attached to the eyewear using a third attachment mechanism;

[0046] Figure 2D shows a rear perspective view of the illumination device attached to the eyewear using a fourth attachment mechanism;

[0047] Figure 2E shows a rear perspective view of the illumination device attached to the eyewear using a fifth attachment mechanism;Figure 2F shows a rear perspective view of the illumination device attached to the eyewear using a sixth attachment mechanism;

[0048] Figure 3A shows a rear perspective view of the illumination device attached to the eyewear using the first attachment mechanism and configured for rotational adjustment of a mirror in two axes using a first alignment mechanism;

[0049] Figure 3B shows a front perspective view of a mirror configured for rotational adjustment in two axes using a second alignment mechanism;

[0050] Figure 3C shows a back view of a mirror configured for rotational adjustment in two axes using the second alignment mechanism;

[0051] Figure 3D shows a top-down view of a mirror configured for rotational adjustment in two axes using the second alignment mechanism;

[0052] Figure 3E shows a left side view of a mirror configured for rotational adjustment in two axes using the second alignment mechanism;

[0053] Figure 3F shows a front perspective view of a mirror configured for rotational adjustment in two axes using the first alignment mechanism;

[0054] Figure 3G shows a front perspective view of a mirror configured for rotational adjustment in two axes using a third alignment mechanism;

[0055] Figure 3H shows a front perspective view of a mirror configured for rotational adjustment in two axes using a fourth alignment mechanism;

[0056] Figure 4A illustrates a side view of a patch being fabricated on a substrate;

[0057] Figures 4B and 4C show, respectively, side perspective views of a planar and curved transparent adhesive patch;

[0058] Figures 5A and 5B show, respectively, a front perspective view and a plan view of a unit cell of the metasurface;

[0059] Figure 6 shows an illustration of the metasurface in operation, conformed to the curved surface of the eyewear lens;

[0060] Figure 7 shows a schematic image of an experimental set-up and resulting images (a)-(d).

[0061] Figures 8A and 8B show top-down views of an illumination device attached, respectively, to a left and right temple of the eyewear with the angle of illumination varied in azimuth and the position of the illumination device selected based on the position of the metasurface;

[0062] Figures 9A and 9B show top-down views of the illumination device attached, respectively, to a left and right temple of the eyewear with the angle of illumination varied in azimuth and the position of the metasurface selected based on the position of the illumination device;

[0063] Figures 10A and 10B show side views of the illumination device attached, respectively, to a left and right temple of the eyewear with the angle of illumination varied in elevation and the position of the metasurface selected based on the position of the illumination device;

[0064] Figures 11A and 11 B show side views of the illumination device attached, respectively, to a left and right temple of the eyewear with the angle of illumination varied in elevation and the position of the illumination device selected based on the position of the metasurface;

[0065] Figures 12A and 12B show side views of the illumination device attached, respectively, to a left and right temple of the eyewear with the angle of illumination varied in elevation when the position of the temple of the eyewear is varied and the position of the metasurface selected based on the position of the illumination device; and

[0066] Figures 13A and 13B show side views of the illumination device attached, respectively, to a left and right temple of the eyewear with the angle of illumination varied in elevation when the position of the temple of the eyewear is varied and the position of the illumination device selected based on the position of the metasurface.

[0067] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0068] Figure 1 shows a rear perspective view of an apparatus 100 for adapting eyewear 102 into augmented reality eyewear according to a first embodiment of the invention. The apparatus 100 comprises at least one transparent adhesive patch 104 (which is shown in more detail in Figures 4A and 4B) having a metasurface 402 thereon comprising reflective content, wherein the patch 104 is configured for adhesion to a lens 110 of the eyewear 102; and an illumination device 112 comprising a light source 116 for illuminating the reflective content for projection 126 onto a user’s retina 118. The illumination device 112 is provided with an attachment mechanism 120 for attachment to the eyewear 102 during use.

[0069] The patch 104 is adhered to an inner surface of the lens 110 at an appropriate position to be illuminated by the light source 116. The illumination device 112 is attached to a temple 128 of the eyewear 102 in a position which is comfortable for the user. The illumination device 112 may be repositioned or removed after use. The eyewear 102 may be constituted by, for example, prescription glasses, safety glasses, toy glasses or sunglasses. In other embodiments, the eyewear 102 may be constituted by goggles or a visor.

[0070] When the patch is illuminated, light 114 is diffracted onto the user’s retina 118 such that the reflective content appears as an image 106 overlaid onto the user’s surroundings. In this example, the image 106 is stationary and in the form of an elephant. In other embodiments, the image 106 may comprise any one or more of letters, writing, symbols, warning signs, logos, or other visual content. In the example shown, a single patch 104 is adhered to a lens 110 of the eyewear 102. In other embodiments, multiple patches are positioned on the lens 110. In some embodiments, one or more patches are adhered to each of the two lenses 110 of the eyewear 102 and, in which case, two illumination devices 112 may be provided with each illumination device 112 attached to a different temple 128.

[0071] In the example shown, the transparent adhesive patch 104 is depicted as a shaded spot. However, in practice the patch 104 and / or metasurface 402 is not visible to a naked eye of a wearer of the eyewear.

[0072] In the example shown, a mirror 122 is angled by an alignment mechanism (not shown).

[0073] Figures 2A through 2F show rear perspective views of the illumination device 112 in detail, but with different attachment mechanisms 120. The illumination device 112 comprises a light source 116 for illuminating the reflective content provided on the lens 110 of the eyewear 102, for projection 126 onto a user’s retina 118; and an attachment mechanism 120 for attachment to the eyewear 102 during use. The light source 116 in this embodiment is a laser but, in other embodiments, may comprise one or more of an LED, a laser and a fibre optic cable.

[0074] The attachment mechanism 120 in Figure 2A comprises a snap-fit component in the form of a snap-fit housing 120a which is configured in a C-shape to snuggly fit around three surfaces of the temple. In the embodiment of Figure 2A, the C-shape fits around a side surface and upper and lower surfaces of the temple 128. In some embodiments, such as that shown in Figure 2F, the C-shape fits around an upper or lower surface of the temple 128 and the side surfaces of the temple 128. The attachment mechanism 120 in Figure 2B comprises two screws 120b located in threaded bore holes through an upper surface of the C-shaped illumination device 112 in order to screw the illumination device 112 onto the temple 128. In other embodiments, attachment mechanism 120 may comprise one or more of: a screw 120b; a clip 120c; a clasp; a clamp; a magnet; a strap; a snap-fit component 120a; and a resilient component. Figure 2B depicts two screws 120b on the upper surface of the illumination device 112. Generally, the illumination device 112 may comprise more than or less than two screws. The screws 120b may be threaded through any surface of the illumination device 112, such as through a side surface as shown in Figure 2F.

[0075] The attachment mechanism 120 in Figure 2C comprises two hinged clips 120c which are used to secure the illumination device 112 to the temple 128 when closed. The main body of the illumination device 112 is C-shaped and fits around a first side surface and upper and lower surfaces of the temple 128. The hinged clips 120c are connected to a bottom edge of the illumination device 112, on the same side as the mirror 122. The hinged clips 120c do not obscure the light emitted by the illumination device 112, when open or closed. The hinged clips 120c are configured to be closed over a second side surface of the temple 128 of the eyewear 102 by raising each hinged clip 120c to meet with a respective one of a pair of fastenings 120e on an upper side face of the illumination device 112. The hinged clips 120c are secured by connecting a fastening 120f on each hinged clip 120c to the respective one of the fastenings 120e on the illumination device 112. In the example shown, the fastenings 120e, 120f are in the form of magnets but, in other embodiments, the fastenings 120e, 120f may comprise one or more of a magnet, snap fixture, buckle, or catch. The illumination device 112 is removable from the temple 128 of the eyewear 102 by detaching the fastenings 120f on the hinged clips 120c from the fastenings 120e on the illumination device 112.

[0076] The attachment mechanism 120 in Figure 2D is similar to that of Figure 2C but with fastenings 120f’ which protrude from each of the hinged clips 120c for receipt within the respective fastenings 120e’, which form sockets therefor.

[0077] The attachment mechanism 120 in Figure 2E is similar to that of Figure 2C but with a single hinged clip 120d, a single fastening 120f” on the hinged clip 120d, and a single corresponding fastening (not shown) on the illumination device 112. The hinged clip 120d is connected to a bottom edge of the illumination device 112, on the opposite side to the mirror 122. In this embodiment, it will be understood that the illumination device 112 has a C-shape that is configured to fit around an inner side surface and upper and lower surfaces of the temple 128, with the attachment mechanism 120 arranged to clip around the outer side surface of the temple 128.

[0078] The attachment mechanism 120 in Figure 2F is similar to that of Figure 2B but with a C-shaped illumination device 112 which is configured to fit around the two side surfaces and upper surface of the temple 128. The attachment mechanism 120 comprises two screws 120b to clamp the illumination device 112 against the first or second side surface of the temple 128. In the example shown, the head of the two screws 120b is on the same side of the illumination device 112 as the mirror 122. In other embodiments, the head of the two screws 120b may be positioned on the opposite side to the mirror 122. In other embodiments the illumination device 112 may be C-shaped and configured to fit around the two side surfaces and the lower surface of the temple 128. The attachment mechanism 120 may comprise one or more screws 120b to clamp the illumination device 112 against the first or second side surface of the temple 128. In other embodiments the attachment mechanism 120 may be C-shaped and fit around a first side surface and upper and lower surfaces of the temple 128. The attachment mechanism 120 may comprise one or more screws 120b to clamp the illumination device 112 against the upper or lower surface of the temple 128. The head of the one or more screws 120b may be positioned on the top or bottom surface of the illumination device 112. Figures 2A through 2F also illustrate the mirror 122 and the polariser 124 which are described in more detail in relation to Figure 7.

[0079] In some embodiments, the light source 116 may be connected to a power supply (not shown) such as an external battery stored somewhere on the user’s body, for example in a pocket of the user’s clothes. In other embodiments, the light source 116 may be connected to an internal battery contained within the illumination device 112. The internal battery may be replaceable, or rechargeable via a wired or wireless connection. The wireless connection may necessitate that an antenna (not shown) be housed within the illumination device 112. In other embodiments, the light source 116 may be provided in the form of a fibre-optic cable connected to an external light source.

[0080] In the example shown, the illumination device 112 is comprised of an opaque material such that the only light 114 which escapes the illumination device 112 illuminates the metasurface 402. In other embodiments, the illumination device 112 may be transparent or semi-transparent.

[0081] In the example shown, the illumination device 112 comprises a single mirror 122 which is configurable to illuminate a single metasurface 402. In other embodiments, the illumination device 112 may comprise at least one beam-splitter (not shown) to split the light from the light source 116 into a transmitted and reflected beam and one or more mirrors 122 configurable to illuminate one or more metasurfaces 402. In some embodiments, a single mirror 122 is configurable to direct both the transmitted and reflected beam onto the one or more metasurfaces 402 during use. In other embodiments, multiple mirrors 122 are configurable to direct at least one transmitted and at least one reflected beam onto the one or more metasurfaces 402. In some embodiments, the illumination device 112 may comprise a sensor (not shown) such that the light source 116 is switched on or off, or the wavelength of the light 114 is adjusted based on an output of the sensor. The sensor may comprise one or more of an electrochemical sensor, a piezoelectric sensor, a temperature sensor, an accelerometer, a magnetometer, an infra-red sensor, or a microphone.

[0082] Figure 3A illustrates a rear perspective view of the illumination device 112 having an alignment mechanism comprised of two screws 302a. In the example shown, the gears 302d extend out of the side and front of the illumination device 112 and are configured such that the angle of the mirror 122 may be adjusted by the user in both azimuth and elevation.

[0083] Figure 3B illustrates a front perspective view of the mirror 122 and an alignment mechanism comprised of two stationary gears (not shown) which are used to adjust the angle of the mirror 122 in two axes. Each stationary gear is configured to interlock with a respective moveable gear 302f which is mounted such that it protrudes through and rotates with respect to a stationary mounting frame 302e. The user may turn each moveable gear 302f which in turn causes the respective stationary gear to adjust the angle of the mirror 122, as the stationary gear 302d is fixed with respect to the mirror 122.

[0084] Figure 3C illustrates a back view of the mirror (not shown) inside the stationary mounting frame 302e of Figure 3B, and the alignment mechanism comprised of the two stationary gears (not shown), and two moveable gears 302f.

[0085] Figure 3D is similar to Figure 3C but illustrates a top-down view of the mirror (not shown) inside the stationary mounting frame 302e, and the alignment mechanism comprised of two stationary gears (not shown), and two moveable gears 302f.

[0086] Figure 3E is similar to Figure 3C but illustrates a left side view of the mirror (not shown) inside the stationary mounting frame 302e, and the alignment mechanism comprised of two stationary gears (not shown), and two moveable gears 302f.

[0087] Figure 3F illustrates a front perspective view of the mirror 122 and an alignment mechanism comprised of two screws 302a which are used to adjust the angle of the mirror 122 in two axes. In the example shown, the screws 302a extend out of the illumination device (not shown) so the angle of the mirror 122 may be adjusted by the user. A tip of a first screw 302a is fixed to a first socket (not shown) on the mirror 122 in the middle of the back of an upper face of the mirror 122. A tip of a second screw 302a is fixed to a second socket (not shown) on the mirror 122 in the centre of the bottom of a back face of the mirror 122. Each respective socket (not shown) is threaded and configured such that rotation of the screws 302a in the sockets in one direction will push against the mirror 122. The screws 302a are threaded through a stationary frame 302e. When the screws 302a are tightened and extend further into the interior of the stationary frame 302e they push on the corners of the mirror 122 to change the angle of the mirror 122 in a first direction. When the screws 302a are loosened and retracted from the interior of the stationary frame 302e they pull on the corners of the mirror 122 to change the angle of the mirror 122 in a second, opposite, direction.

[0088] Figure 3G illustrates a front perspective view of the mirror 122 and an alignment mechanism comprised of two screws 302a which are configured to adjust the angle of the mirror 122 in two axes. In the example shown, the screws 302a are used to loosen and tighten springs (not shown) which connect two plates 302b, thereby adjusting the angle of the mirror 122 mounted in the centre of the front face of the front plate 302b. The rear plate 302b is fixed while the front plate 302b is moveable. The screws 302a are threaded through opposite corners of the front face of the front plate 302b and extend into the rear plate 302b. In the example shown, the screws 302a extend out of the illumination device (not shown) so the angle of the mirror 122 may be adjusted by the user.

[0089] Figure 3H illustrates a front perspective view of the mirror 122 and an alignment mechanism comprised of a ball joint 302c which is configured to adjust the angle of the mirror 122 in two axes. In the example shown, the ball joint 302c is fixed to a mounting plate 302g on which the mirror 122 is mounted. In other embodiments, the ball joint 302c may be fixed directly to the mirror 122. The ball joint 302c allows the angle of the mirror 122 to be adjusted in any axis. In the example shown, three rods 302h are fixed to the mirror 122 and extend out of the illumination device (not shown) such that the user can manipulate the rods 302h to thereby adjust the angle of the mirror 122. In other embodiments, screws 302a or gears 302f could be used to adjust the angle of the mirror 122.

[0090] Figure 4A illustrates a side view of a patch being fabricated. Fabrication methods for the patch are not limited to the embodiments shown and any suitable fabrication method may be employed. More specifically, Figure 4A shows a rigid carrier 408 in the form of a glass wafer which is coated with a release layer 410 before the application of a substrate 406. In other embodiments, the rigid carrier 408 may comprise any one of a silicon wafer, a microscope slide, a small piece of silicon, or a small piece of glass. In the embodiment shown, the rigid carrier 408 is coated with Omnicoat™ adhesion promoter which serves as the release layer 410. In other embodiments, the release layer 410 may be comprised of one or more of: a salt such as potassium chloride, a metal such as aluminium, or a polymer layer such as polydimethylsiloxane.

[0091] In the example shown, the patch 104 is formed on a 10 pm-thick SU-8 substrate 406. In other embodiments, the substrate 406 may be parylene, polydimethylsiloxane, cyclic olefin polymer, poly(methylmethacrylate), or any other transparent conformable thin-film material. The substrate 406 may be from the order of micrometres to hundreds of micrometres thick. In the present example, the substrate 406 is formed from material that is spin-coated onto the release layer 410 on the rigid carrier 408 before curing, which allows several metasurfaces 402 to be fabricated on a single rigid carrier 408. In one embodiment, the substrate 406 is sealed with poly(methylmethacrylate) around its edges to prevent dissolution of the release layer 410 during resist development.

[0092] In other embodiments, the substrate 406 may be formed by applying a material to the rigid carrier 408 by dip-coating or doctor blading. In some embodiments, the substrate 406 may be purchased as a commercially available film before being adhered to the rigid carrier 408 using any one or more of adhesive tape, polyimide tape, or photoresist.

[0093] In Figure 4A, the metasurface 402 is formed on the substrate 406 by applying a coating of a 3 nm-thick adhesion layer (not shown) of nickel-chromium, using evaporation. The adhesion layer is subsequently coated with a 150 nm-thick gold layer, using evaporation, which forms a base metal layer 504 (shown in Figure 5A). A middle insulator layer 506 (shown in Figure 5A) is spin-coated onto the base metal layer 504 and patterned using electron-beam lithography before being development in Ma-D 525 developer solution. A top metal layer 508 (shown in Figure 5A) is applied to the middle insulator layer 506 using evaporation in order to complete a nanorod 502. In practice, multiple nanorods 502 will be fabricated at the same time to form the metasurface 402. In other embodiments, the metal layers may be applied using sputtering techniques.

[0094] In Figure 4A, the periphery of the metasurface 402 is defined by applying a protective layer (not shown) of S1805 and S1818 photoresist to the metasurface 402 and leaving unwanted portions of the base metal layer 504 on the surface of the patch 104 unprotected. The unwanted portions of the base metal layer 504 and underlying nickelchromium are etched using wet etching. The protective photoresist is then removed using Microposit™ 1165 photoresist stripper.

[0095] In other embodiments, the periphery of the metasurface 402 is defined using one of more of: lift-off photolithography techniques, dry etching, wet etching. In other embodiments, the protective layer may be comprised of any one or more of: photoresist, electron-beam resist, metal, polymer.

[0096] After the metasurface 402 is formed, the substrate 406 is removed from the rigid carrier 408. In the present example, the substrate 406 is released by dissolving the release layer 410 of OmniCoat™ adhesion promoter with MF-319, a tetramethylammonium hydroxide-based alkaline photoresist developer. In other embodiments, a release layer 410 comprising a salt may be removed by soaking in water; a release layer 410 comprising a metal may be removed by wet etching or electrolysis; and a polymer may allow the substrate 406 to be peeled off after the metasurface 402 has been formed. Once removed from the rigid carrier 408, the substrate 406 is separated into individual patches 104 by cutting. In one or more embodiments, the patches 104 are separated by etching, dicing or any other appropriate method. In one or more embodiments, there are several metasurfaces 402 on a single patch 104

[0097] Figures 4B and 4C show the transparent adhesive patch 104 configured for adhesion to the lens 110 of the eyewear 102 to adapt the eyewear 102 into augmented reality eyewear. The transparent adhesive patch 104 comprises the metasurface 402 thereon comprising reflective content in the form the nanorods 502. Figure 4B illustrates the patch 104 as fabricated, when no force is applied to the patch 104 and it is placed on a planar surface (not shown). Figure 4C illustrates the flexibility and / or conformability of the patch 104 which allows it to better adhere to a curved surface of the lens 110 of the eyewear 102.

[0098] In the example shown, the patches 104 are backed by an adhesive Iayer 412 and secured to a release paper (not shown) for supply to a user. In other embodiments, the patch 104 is inherently adherent as a result of the material of the substrate 406, and is secured to a release paper without the addition of an adhesive layer 412. The user can then peel off the patch 104 from the release paper and stick the patch 104 onto the eyewear 102, using the adhesive 412, if provided thereon.

[0099] In some embodiments, the patch 104 may serve as a sensor. The image 106 projected onto the user’s retina 118 may change depending on an output from the sensor, for applications including but not limited to an enhanced warning system for partially sighted wearers and / or to highlight environmental information. The patch 104 may comprise one or more of a gas sensor, an electrochemical sensor, a piezoelectric sensor, a temperature sensor and an infra-red sensor. For example, the metasurface 402 may be configured to change state in the presence of a particular element or molecule (e.g. in a gas in the atmosphere). The presence of the molecule may alter the properties of the metasurface 402 such that an image 106 in the form of a warning is projected into the user’s eye. The absence of the molecule will cause the metasurface 402 to be in a non-warning state such that no image 106 is projected.

[0100] In the example shown, the metasurface 402 is circular and the diameter is less than the width and length of the transparent adhesive patch 104, which is approximately 300 pm. In other embodiments, the metasurface 402 may be formed as a layer extending over an area having a periphery that is generally square, rectangular, triangular, or any other two-dimensional shape when in plan view. The reflective content is formed in the metasurface 402 by the plurality of nanorods 502 provided in unit cells 500 (also known as subcells) as shown in Figures 5A and 5B.

[0101] Figure 5A shows a perspective view of a single unit cell 500 of the metasurface 402. The unit cell 500 is repeated with period P over a significant portion of the area of the metasurface 402. In the example shown, P is equal to 600 nm. Each unit cell contains a nanorod 502 also known as a nanopillar comprised of two layers formed on a surface of the base metal layer 504. The base metal layer 504 extends over the area of the metasurface 402, which is fabricated on the transparent adhesive patch 104 (not shown). The base metal layer 504 has a thickness (i.e. height) of Tb. In the example shown, Tb is equal to 150 nm. The middle insulator layer 506 in the form of a cuboid is formed on the base metal layer 504. The middle insulator layer 506 has a thickness (i.e. height) of Tm. In the example shown, Tmis equal to 410 nm. The top metal layer 508 in the form of a cuboid is formed on the middle insulator layer 506. The top metal layer 508 has a thickness (i.e. height) of Tp. In the example shown, Tpis equal to 40 nm. The nanorod 502 has a length L and a width W. In the example shown, L is equal to 239 nm and W is equal to 149 nm.

[0102] Figure 5B is a top-down view of the unit cell 500 including the nanorod 502. This view shows that the nanorod 502 is provided on the base metal layer 504 with the length L rotated by an angle of rotation 0 when compared to a direction of the period P. The unit cells 500 have dimensions and materials that are substantially the same across the metasurface 402, although the angle of rotation 0 may be varied to control the optical properties of the metasurface 402 to produce the reflective content. In the example shown, the nanorod 502 is a metal-insulator-metal Pancharatnam-Berry meta-atom. In other embodiments, the nanorod 502 may be all-metal or all-dielectric. In the example shown, an Optimised Gerchberg-Saxton algorithm is combined with a Raleigh- Sommerfield diffraction integral to compute an initial phase distribution of the metasurface 402. The metasurface 402 is fabricated with a final phase distribution including an additional phase shift added to the initial phase distribution to address a uniform phase delay associated with off-axis illumination from the illumination device 112.

[0103] In some embodiments, the phase distribution of the nanorods 502 may be engineered such that the image 106 projected onto the user’s retina 118 changes when the metasurface 402 is applied to lenses 110 with different radii of curvature.

[0104] In the example shown, the base metal layer 504 and top metal layer 508 of each unit cell 500 is gold, although in other embodiments the base metal layer 504 and / or the top metal layer 508 may be formed from another reflective metal. In the example shown, the middle insulator layer 506 is formed from Ma-N2403 electron-beam resist. Generally, the middle insulator layer 506 may be any insulator material which can be patterned with nanometre-scale precision, such as a photoresist or electron-beam resist. The patterning may also be achieved by any one or more of: dry etching a planar layer; wet etching a planar layer; nanocasting.

[0105] Figure 6 shows an illustration of the metasurface 402 in use, although not all features of the eyewear 102 and illumination device 112 are shown for ease of illustration. The patch 104 is conformed to a curved inner surface of the lens 110. Light 114 from the light source 116 is reflected off the metasurface 402 and the resulting projection 126 on the retina 118 produces the appearance, to the user, of the image 106 overlaid on their real world surroundings 602 in a field of view 600.

[0106] Figure 7 shows a schematic image of an experimental set-up 700 and resulting images (a)-(d) similar to the apparatus 100 in which the illumination device 112 is configured for side illumination of the metasurface 402.

[0107] In the set-up 700, there is provided a light source 116 in the form of a laser configured to emit light 114 which passes through a linear polarizer 702 and a quarterwave plate 704 before being incident on the inclined metasurface 402, resulting in the projection 126 of the image 106 onto a camera 706, which simulates the retina 118.

[0108] When the light source 116 is switched off for image (a), the metasurface 402 is not visible against the surroundings 600 to a naked eye of a wearer of the eyewear 102. In general, the light source 116 may be configured to emit light 114 any at one or more wavelengths in the visible spectrum. For image (b) the laser illuminates the metasurface 402 at 650 nm. For image (c) the laser illuminates the metasurface 402 at 532 nm. For image (d) the laser illuminates the metasurface 402 at 488 nm. The illumination device 112 of Figure 2A and 2B comprises a polarizer 124 configured to polarise light 114 from the light source 116 prior to incidence on the metasurface 402 during use. The light 114 may be linearly polarised, for example by the linear polarizer 702. In the example shown, the light 114 is circularly polarised by the linear polarizer 702 and the quarter-wave plate 704.

[0109] In the example shown in Figure 7, the light source 116 is positioned at an angle of illumination a. In other embodiments, the illumination device 112 comprises a mirror 122 configurable to direct light 114 from the light source 116 onto the metasurface 402 during use. Therefore, the light source 116 may be positioned at any angle of illumination a, provided the mirror 122 is configured to reflect the light 114 onto the metasurface 402. In the example shown, a zero-order diffracted light 708 is directed away from the camera 706, whereas the image 106 is projected into the camera’s field of view 600.

[0110] In the example shown, the image 106 appears larger when the wavelength of light 114 incident on the metasurface 402 increases.

[0111] In the example shown, the metasurface 402 is illuminated with light 114 of a single wavelength at any one time. In other embodiments, the metasurface 402 could be illuminated by several wavelengths of light 114 simultaneously, each with a different angle of illumination a in order to produce a full colour image 106.

[0112] In the example shown, the metasurface 402 is designed to enhance absorption rather than increase scattering in a non-laser wavelength range such that the metasurface 402 is not influenced by other light sources and will not generate images 106 when the light source 116 is switched off.

[0113] In the example shown, zero-order diffracted light 708 is not directed towards the camera 706 which facilitates distinction between the zero-order diffracted light 708 and the image 106.

[0114] The illumination device 112 is configured to emit light 114 at an angle of illumination aaof approximately 20° to 80° or -20° to -80° in azimuth and / or at an angle of illumination aeof approximately 20° to 80° or -20° to -80° in elevation with respect to a longitudinal axis of the temple 128.

[0115] Figures 8A and 8B show top-down views of an illumination device 112 attached, respectively, to a left and right temple 128 of the eyewear 102 with the angle of illumination aavaried in azimuth and the position of the illumination device 112 selected based on the position of the metasurface 402 on the lens 110. The position of the metasurface 402 and / or the angle of illumination aamay be selected to accommodate the pupil distance d of the individual user. Figures 9A and 9B show top-down views of the illumination device 112 attached, respectively, to a left and right temple 128 of the eyewear 102 with the angle of illumination aavaried in azimuth and the position of the metasurface 402 selected based on the position of the illumination device 112. The position of the illumination device 112 may be selected or adjusted to accommodate different facial features of individual users, and for user comfort. The position of the illumination device 112 may be adjusted to accommodate different designs of eyewear 104, for example eyewear 104 with ornate temples 128, hinges or end pieces may prevent the illumination device 112 from being attached to a portion of the temple 128 which is closest to the eyes. The position of the illumination device 112 may be adjusted to accommodate temples 128 with different shapes, thicknesses or heights.

[0116] Figures 10A and 10B show side views of the illumination device 112 attached, respectively, to a left and right temple 128 of the eyewear 102 with the angle of illumination aevaried in elevation and the position of the metasurface 402 selected based on the position of the illumination device 112. The position of the illumination device 112 may be selected or adjusted to accommodate different facial features of individual users, and for user comfort. The position of the illumination device 112 may be adjusted to accommodate different designs of eyewear 104, for example eyewear 104 with ornate temples 128, hinges or end pieces may prevent the illumination device 112 from being attached to the portion of the temple 128 which is closest to the eyes. The position of the illumination device 112 may be adjusted to accommodate temples 128 with different shapes, thicknesses or heights.

[0117] Figures 11A and 11 B show side views of the illumination device 112 attached, respectively, to a left and right temple 128 of the eyewear 102 with the angle of illumination aevaried in elevation and the position of the illumination device 112 selected based on the position of the metasurface 402. The position of the metasurface 402 may be adjusted to accommodate the pupil height h of the individual user.

[0118] Figures 12A and 12B show side views of the illumination device 112 attached, respectively, to a left and right temple 128 of the eyewear 102 with the angle of illumination aevaried in elevation when the position of the temple 128 of the eyewear 102 is varied and the position of the metasurface 402 selected based on the position of the illumination device 112. The position of the illumination device 112 may be selected or adjusted to accommodate different facial features of individual users, and for user comfort. The position of the illumination device 112 may be adjusted to accommodate different designs of eyewear 104, for example eyewear 104 with ornate temples 128, hinges or end pieces may prevent the illumination device 112 from being attached to the portion of the temple 128 which is closest to the eyes. The position of the illumination device 112 may be adjusted to accommodate temples 128 with different shapes, thicknesses or heights.

[0119] Figures 13A and 13B show side views of the illumination device 112 attached, respectively, to a left and right temple 128 of the eyewear 102 with the angle of illumination aevaried in elevation when the position of the temple 128 of the eyewear 102 is varied and the position of the illumination device 112 selected based on the position of the metasurface 402. The position of the metasurface 402 may be adjusted to accommodate the pupil height h of the individual user, and different designs of eyewear 102 wherein the position of the temple 128 of the eyewear 102 is varied.

[0120] Thus, embodiments of the invention provide an apparatus 100 comprising an illumination device 112 and a patch 104, which can be attached to any eyewear 102 to adapt the eyewear 102 into augmented reality eyewear.

[0121] The skilled person will understand that in the preceding description and appended claims, positional terms such as ‘top, ‘upper, ‘side’, etc. are made with reference to conceptual illustrations, such as those shown in the appended drawings. These terms are used for ease of reference but are not intended to be of limiting nature. These terms are therefore to be understood as referring to an object when in an orientation as shown in the accompanying drawings.

[0122] Although the disclosure has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in any embodiments, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

Claims

CLAIMS:1 . Apparatus for adapting eyewear into augmented reality eyewear, comprising: at least one transparent adhesive patch having a metasurface thereon comprising reflective content, wherein the patch is configured for adhesion to a lens of the eyewear; and an illumination device comprising a light source for illuminating the reflective content for projection onto a user’s retina; wherein the illumination device is provided with an attachment mechanism for attachment to the eyewear during use.

2. The apparatus of claim 1 wherein the illumination device is configured for attachment to a temple of the eyewear.

3. The apparatus of claim 1 or 2 wherein the illumination device is configured for side illumination of the metasurface.

4. The apparatus of claim 3, when dependent on claim 2, wherein the illumination device is configured to emit light at an angle of illumination of approximately 20° to 80° or -20° to -80° in azimuth and / or at an angle of illumination of approximately 20° to 80° or -20° to -80° in elevation with respect to a longitudinal axis of the temple; optionally wherein the angle of illumination in elevation is less than the angle of illumination in azimuth.

5. The apparatus of any preceding claim wherein the illumination device comprises a mirror configurable to direct light from the light source onto the metasurface during use; optionally, wherein the mirror comprises an alignment mechanism configured to change a direction of light reflected from the mirror.

6. The apparatus of any preceding claim wherein the illumination device comprises a polarizer configured to polarise light from the light source prior to incidence on the metasurface during use.

7. The apparatus of any preceding claim wherein the light source comprises one or more of an LED, a laser and a fibre optic cable.

8. The apparatus of any preceding claim wherein the light source is configured to emit light at two or more wavelengths.

9. The apparatus of any preceding claim wherein the metasurface is fabricated with a phase distribution including an additional phase shift to address a uniform phase delay associated with off-axis illumination.

10. The apparatus of any preceding claim wherein the metasurface is configured such that it does not impair the normal vision of the user when the light source is off.11 . The apparatus of any preceding claim wherein the patch is conformable to a curved surface of the lens.

12. The apparatus of any preceding claim wherein the attachment mechanism comprises one or more of: a screw; a clip; a clasp; a clamp; a magnet; a snap-fit component; and a resilient component.

13. The apparatus of any preceding claim wherein the eyewear may be constituted by prescription glasses, safety glasses, toy glasses or sunglasses.

14. An illumination device for use in adapting eyewear into augmented reality eyewear, comprising: a light source for illuminating reflective content provided on a lens of the eyewear, for projection onto a user’s retina; and an attachment mechanism for attachment to the eyewear during use.

15. A transparent adhesive patch configured for adhesion to a lens of an eyewear to adapt the eyewear into augmented reality eyewear, comprising: a metasurface thereon comprising reflective content.

Images