Encapsulation of thin film within eyeglass lens

Abstract

To provide a less complex manufacturing technique or a manufacturing technique for integrating a thin film with an eyeglass lens without risk of deformations and / or delamination of the thin film.SOLUTION: An eyeglass lens comprises: a first lens part affixed to a second lens part with a cylindrically-shaped interface therebetween; and a thin film interposed between the first and second lens parts at the cylindrically-shaped interface. A method of manufacturing eye glass lens comprises interposing the thin film between the first lens part and the second lens part, at a cylindrically-shaped interface between the first and second lens parts.SELECTED DRAWING: Figure 3B

Description

[Technical field]

[0001] The present disclosure relates to spectacle lenses having encapsulated thin films, and lens manufacturing and / or thin film encapsulation techniques for producing spectacle lenses having encapsulated thin films. [Background technology]

[0002] Spectacle lenses are typically manufactured through lens grinding or injection molding techniques. The injection molding process for spectacle lenses consists of injecting molten material under high pressure into a mold. The mold is shaped with either a blank shape (to create a lens "blank" with the intention of further shaping the inner surface to create the final lens) or the exact contour of the desired spectacle lens, including the inner and outer curvature profiles. After a short cooling period, the lens is finished. Due to the ease and speed of this process, injection molding is the technique of choice for large batches of lenses and stock lenses, such as sunglasses. For more custom applications, lens grinding techniques are preferred. The lens grinding process begins with a lens "blank" that has a convex outer (outward facing) surface and a flat or concave eye-facing surface. The curved surface(s) of these blanks are typically spherical or spherocylindrical in profile. The inner surface is then ground and polished to the desired curvature profile using specialized machinery. The eyeglass lenses are then edged with the desired edge profile to fit within the frame, completing the eyeglasses. With the advent of 3D printing (or additive manufacturing) technology, it is also possible to 3D print eyeglass lenses with completely custom curvatures and edge profiles.

[0003] It is desirable for many purposes to deposit thin films onto or encapsulate within eyeglass lenses. For example, the Augmented Reality (AR) industry (including eye tracking applications) desires holographic optical elements (HOEs) that can be produced on thin polymer films that are then affixed to or encapsulated within eyeglass lenses.

[0004] There are existing techniques for encapsulating thin films in or laminating thin films onto eyeglasses. For example, US Patent Publication No. 2015 / 0131047A1 details a process for direct lamination of cellulose acetate lamination films onto eyeglasses of various profiles for use in protective eyewear. US Patent Publication No. 2017 / 0068095A1 describes a number of techniques. In the first of these, the lens is injection molded, thereby creating a mold with a cavity for positioning the HOE photopolymer film before casting. Eyeglass material is then injected into the mold, encapsulating the HOE therein. The second technique encapsulates the HOE between two lens halves, including the rear portion of the eyeglass lens and the front portion of the eyeglass lens. The HOE is sandwiched at the interface of the two eyeglass lens components. In the third technique, the photopolymer film is laminated directly onto the concave inner surface of the eyeglass lens.

[0005] Known approaches involve complex manufacturing techniques or the risk of deformation and / or delamination of the thin film. Therefore, less complex manufacturing techniques are desired for integrating the thin film with the spectacle lens without such significant difficulties. Summary of the Invention

[0006] Against this background, a spectacle lens according to claim 1 and a method for manufacturing a spectacle lens in accordance with claim 8 are provided. A technique for making a spectacle lens with an encapsulated thin film, and a resulting spectacle lens with an encapsulated thin film that has minimized stresses and deformations, are provided. This is achieved by providing a thin film on a cylindrically shaped interface between two parts of the spectacle lens.

[0007] It has been found that many of the stresses and deformations when encapsulating thin films within lenses are induced by lamination onto curved surfaces, specifically surfaces that are curved across two axes, as in a typical eyeglass lens. Laminating a film directly onto a surface with a spherical curvature (or other curvature profile across two axes, which is often chosen for minimum thickness) creates elastic stresses in the film, leading to deformation and delamination.

[0008] In contrast, it has been found that such stresses are avoided when laminating thin films on cylindrical surfaces. For completeness, it is noted that a cylindrical surface means that the surface has the shape of a portion of a cylinder along its axis of extension. In other words, the surface is curved (e.g., circular or elliptical) along one dimension, but straight (or flat) along the perpendicular dimension. Cylindrical interface surfaces are highly unconventional, especially since they do not conform to the shape of spectacle lenses and are therefore perceived as non-compact. However, cylindrical interface surfaces may still provide low thickness without difficulties in lamination.

[0009] Thus, a spectacle lens may be produced using two component parts with a thin film encapsulated between them. Thus, a lens may be made using two components, a posterior (eye-facing) section and an anterior (outward-facing) section. The interface between the two components has the cylindrical shape described above. In other words, taking a cross section along one plane, preferably a plane parallel to the major axis (usually horizontal), the interface is shown to be curved (e.g., a circular or elliptical section). A cross section along a vertical plane, typically parallel to the minor axis (generally vertical), is preferably flat or straight. Limiting the curvature across the minor axis (preferably to zero) allows for the thinnest stack and imposes the least restrictions on the choice of inner and outer curvatures.

[0010] In the simplest case, a lens with a spherical or spherocylindrical outer profile (typically similar to a regular prescription eyeglass lens) can be split or formed into two component parts, the interface between the two components being the interface of the cylindrical profile. By laminating a thin firm onto a cylindrical surface, the risk of deformation and delamination is reduced. Since this surface has curvature only in one axis, it does not induce the same stresses on the thin film compared to lamination on a spherical surface.

[0011] The two parts may be made by any technique, for example injection molding techniques typically used for batch production, grinding and polishing techniques often used for more bespoke requirements, or 3D printing. Optionally, the membrane may be integrated with one of the lens parts (so as to be located at the formed interface), for example by positioning the membrane in a mold before casting. After the two lens parts are joined with the membrane inserted between them (regardless of whether either lens part is integrally formed with the membrane), the resulting spectacle lens may be considered a blank. The eye-facing surface of the blank may then be milled to form the spectacle lens.

[0012] A typical eyeglass lens is a meniscus lens, meaning that the surface facing the eye is concave and the surface facing outward is convex. A typical eyeglass lens also exhibits a certain aspect ratio (thereby defining a major and minor axis), whereby the horizontal extent (major axis) of the lens is greater than the vertical extent (minor axis). Advantageously, this aspect ratio allows the eyeglass lens to be bisected into two components for the purpose of encapsulating a thin film.

[0013] The thin film is preferably anisotropic. Typically, the thin film includes a holographic optical element (HOE) that can act as a reflective or transmissive element. In some embodiments, the HOE can act as a plane mirror or a plane transmission hologram without any refractive power. Alternatively, the HOE can apply a refractive power such that the total refractive power of the HOE is the sum of the refractive power of the hologram and the refractive power due to the curvature of the cylindrically shaped interface.

[0014] The thin film may initially be a photosensitive material, and the HOE may be formed by recording a hologram on the photosensitive material. In some embodiments, the hologram may be recorded when the photosensitive material is on a planar substrate and then laminated to the cylindrical interface. In that case, the hologram is advantageously recorded to compensate for the cylindrical interface. In other embodiments, the hologram may be recorded when the photosensitive material is applied to the cylindrical interface. In that case, no additional compensation for the cylindrical interface is required.

[0015] Combinations of aspects or features from the aspects may also be considered where such combinations are practicable.

[0016] The present disclosure may be practiced in numerous ways, and preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings. [Brief description of the drawings]

[0017] [Figure 1] 1 shows a perspective view of an existing eyeglass lens. [Figure 2A] 1 illustrates a perspective view of a spectacle lens according to the present disclosure; [Figure 2B] 2B illustrates a cross section through the eyeglass lens of FIG. 2A. [Figure 3A] 2B illustrates the component parts of the eyeglass lens of FIG. 2A. [Figure 3B] 3B illustrates diagrammatically the assembled configuration of the component parts of FIG. 3A; [Figure 4A] 1 shows a perspective view of an example of an alternative eyeglass lens. [Figure 4B] 4B illustrates a cross section through the eyeglass lens of FIG. 4A. [Figure 5A] 4B illustrates the component parts of the eyeglass lens of FIG. 4A. [Figure 5B] 5B illustrates diagrammatically the assembled configuration of the component parts of FIG. 5A. [Figure 6A] An example of a circular lens blank is illustrated. [Figure 6B] 6B illustrates an exploded view of the lens blank of FIG. 6A bisected according to a planar interface. [Figure 6C] 6B illustrates an exploded view of the lens blank of FIG. 6A bisected according to a cylindrically shaped interface. [Figure 7] 1 illustrates a schematic diagram of the relationship between radius of curvature and center thickness for the size of a spherically shaped outwardly facing lens component. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The drawings are all schematic in nature and precise dimensions and configurations should not be inferred unless explicitly shown or described.

[0019] 1, there is shown a perspective view of an existing eyeglass lens 101 having an eye-facing surface 102 and an outwardly facing surface 103. This is a simple non-prescription spherical lens (like the other eyeglass lenses shown in the figures) and is used for illustrative purposes only. It will be appreciated that the embodiments may be applied to other eyeglass lenses, including prescription eyeglass lenses, and eyeglass lenses having a variety of curve profiles.

[0020] A typical eyeglass is a meniscus lens, meaning that the surface 102 facing the eye is concave and the surface 103 facing outward is convex. As mentioned above, the eyeglass lens 101 shown has a spherical radius of curvature on both the inner and outer surfaces. Simple spherical lenses are often used for non-prescription stock lenses, in applications including sunglasses and ski goggles. In this application, both the anterior and posterior surfaces have a spherical curvature where the two curvature profiles are concentric. For prescription lenses, a cylindrical power is often added to the posterior lens surface 102 to correct astigmatism. However, the surfaces are usually spherocylindrical (as explained in “Principles of Ophthalmic Lenses”, MJ alie, Association of British Dispensing Opticians College of Education). Typical dimensions of eyeglass lenses are shown for illustrative purposes only.

[0021] 1 also shows axes that are used consistently in other figures of this disclosure. The eyeglass lens 101 typically has a major axis in the horizontal (x) direction and a minor axis in the vertical (y) direction. The depth (z) dimension of the eyeglass lens 101 is typically negligible (or at least significantly smaller, usually by a factor of at least 10) compared to the size of the other dimensions.

[0022] Spectacle lenses typically have a spherical curvature on the outer (outward facing) surface, commonly known as the "base curvature". This base curvature serves a functional purpose in providing the best optical performance of the lens, while also improving aesthetics and reducing the weight of the lens. A front surface of 6 diopters of curvature (corresponding to a radius of curvature of approximately 83 mm) is considered the "best form" (based on empirical data) to give the best peripheral vision. Reading glasses and fashion lenses often have a slightly flatter surface for aesthetic reasons, and a 4 diopter base curve is common.

[0023] For further information (but again, not by way of specific limitation), note that the spectacle lens 101 shown has a horizontal lens extent (along the x-axis) of 55 mm and a vertical lens extent (along the y-axis) of 32 mm. The lens has a uniform thickness of 2 mm, an inner (eye-facing) radius of curvature of 150 mm (approximately 3.3 diopters), and an outer (outward-facing) radius of curvature of 152 mm. This is typical of non-prescription stock lenses, although as noted above, 6 diopter or 4 diopter lenses may be more common. Prescription lenses will have a variety of thickness profiles.

[0024] Reference is now made to FIG. 2A, which shows a perspective view of a spectacle lens 201 according to the present disclosure. According to the present disclosure, a thin film is encapsulated in the spectacle lens by forming the spectacle lens in two components, and the interface between the two components is a cylindrical profile. Although the parameters of the thin film are generally well understood, in this context, the thin film may have a thickness on the order of 100 microns or less. This is typically a low-absorption, optically clear (or transparent) low-haze film, suitable for incorporation into the lens without significantly affecting the view through. A reference plane 202 at the center of the spectacle lens is highlighted in the xz plane. Reference is also made to FIG. 2B, which illustrates a cross section through the spectacle lens of FIG. 2A at the reference plane 202. Here, the cylindrical interface profile 203 between the two component parts is shown as a dashed line.

[0025] The two component parts are typically fabricated separately, but may optionally be formed from a split spectacle lens. A cylindrical surface on the lens or lens components is not typical. A cylindrical surface between the two lens components may be created by grinding or by a custom mold (injection molding). Optionally, 3D printing may be used to create the lens components. Manufacturing lens components with cylindrical interfaces is not a standard technique. Nevertheless, it is possible to use injection molding (e.g., of plastic), grinding, or 3D printing. Standard lens grinding and mold manufacturing may use diamond turning, which usually implies a spherical surface, but this and other techniques may be used instead to achieve a cylindrical surface.

[0026] Referring now to Figure 3A, the component parts of the spectacle lens of Figure 2A are illustrated. These comprise a first component part (incorporating the eye-facing surface) 301 and a second component part (incorporating the outwardly facing surface) 302. The interface between the first component part 301 and the second component part 302 has a cylindrical shape (as shown in Figure 2B) that is curved in the xz-plane (in this case a circular segment) and flat in the yz-plane (and also flat in the xy-plane).

[0027] In this example, the cylindrical shape is specifically curved with a radius of curvature of 151 mm in the x-axis, and the profile is flat in the y-axis. It can therefore be seen that the use of a purely cylindrical interface between the two parts allows for the formation of two components, each having component dimensions of 55 mm (x) by 32 mm (y) (the same dimensions as the major and minor axes of the spectacle lens), which can be combined to create the final spectacle lens. The thickness of the center of each component is approximately 1.3 mm.

[0028] A thin film (not shown in FIG. 3A) of the same size (55 mm in x-dimension and 32 mm in y-dimension) and profile as a pair of glasses is laminated onto the cylindrical interface between the first component part 301 and the second component part 302. The thin film is then fully encapsulated within the eyeglass lens when the first component part 301 and the second component part 302 are attached to each other. Lamination onto a cylindrical surface avoids the deformations associated with lamination onto a spherical surface. The interface is preferably purely cylindrical, but can be partially sphero-cylindrical or toric, as long as any deviation from a purely cylindrical shape is negligible. The closer the interface is to a perfect cylinder, the more stresses in the thin film are minimized. The thin film is preferably a holographic optical element (HOE) or a photosensitive material suitable for recording a HOE therein.

[0029] As mentioned above, the cylindrical interface between the first component part 301 and the second component part 302 is flat in one axis. This axis therefore presents the same geometrical constraints as using a flat membrane. However, because spectacle lenses typically have a significant aspect ratio, this constraint becomes less important when applied only over the shorter (minor) axis of the spectacle lens, as will be discussed further herein below.

[0030] Attachment of the thin film to the cylindrically shaped surface of one of the lens components may be accomplished in a number of ways. Lamination of the thin film may not require adhesion of the thin film to one or both surfaces of the cylindrical interface (the first component part 301 and the second component part 302 may simply be attached to each other with the thin film between them), although additional adhesion may be provided. The HOE may be a photopolymer, for example Bayfol(RTM) HX (commercially available from Covestro AG), which typically has a substrate about 60 microns thick and a polymer layer about 20 microns thick. One side of the photopolymer is then typically a sticky film that adheres to glass or plastic when laminated onto a surface using a roller (or similar). Alternatively or additionally, the HOE may be attached to the substrate using adhesives, double-sided tape, vacuum treatment, heat treatment, or pressure treatment. Alternatively, the HOE may be a silver halide film, and the techniques described above may also be used to adhere the thin film to the substrate surface. The choice of lens material can aid in adhesion, for example polycarbonate may give better adhesion. The membrane typically does not extend very far to the edge of the cylindrical interface. This allows for better encapsulation (no moisture ingress) if there is a good adhesive seal all around.

[0031] Referring to Figure 3B, there is illustrated diagrammatically a spectacle lens 303 assembled from the component parts of Figure 3A. Also shown is a membrane 304 encapsulated between a first component part 301 and a second component part 302. Thus, the completed spectacle lens 303 is created by two component parts fitted together by a cylindrical interface with the membrane 304 between them.

[0032] The eye-facing component (first component part 301) may be molded in the desired shape for a spectacle lens. More typically, the component is molded as a lens blank with a cylindrical profile on the front surface (bonded to the outwardly facing component 302), although the back surface may be flat or have any arbitrary surface curvature. The first component part 301, second component part 302, and thin film 304 are then bonded to form the spectacle lens 303 as a lens "blank" with an embedded HOE.

[0033] Once the assembled eyeglass lens 303 is formed in this way, it appears as a circular profile lens blank, and the rear surface can be milled as a standard lens blank to produce the final lens. To fit the eyeglasses, the front and rear curvatures are typically edge machined (milled around the edges) to fit within the eyeglass frame. This machining can be performed on the first component part 301 and the second component part 302 before the encapsulation of the membrane and assembly, or after assembly. The grinding process, when the front and / or rear surfaces are ground into a curvature, is a more intense process than edge machining, and if necessary, this is preferably performed on the first component part 301 and / or the second component part 302 before the encapsulation of the membrane and assembly.

[0034] Thus, the outwardly facing component is typically formed with an anterior surface, typically spherical, with a desired base curvature, and a posterior surface with a cylindrical profile. The eye-facing component may be formed with an anterior surface with a cylindrical profile, and a posterior surface. This posterior surface may be formed with a desired curvature for the final power setting. Alternatively, the posterior surface may remain flat (or with any curvature) to create the lens blank, whereby further milling of this surface will be used to set the power setting.

[0035] Now referring to FIG. 4A, a perspective view of an example of an alternative eyeglass lens 401 is shown. This alternative eyeglass lens 401 does not have a cylindrical interface between two lens components, but rather a planar interface. This is shown for comparison purposes. A reference plane 402 in the center of the eyeglass lens is highlighted in the xz plane. Also referred to FIG. 4B, which illustrates a cross section through the eyeglass lens of FIG. 4A at the reference plane 402. Here, the planar (flat) interface profile 403 between the two component parts is shown as a dashed line.

[0036] Referring now to FIG. 5A, the component parts of the spectacle lens of FIG. 4A are illustrated. They comprise a first component part 501 (incorporating an eye-facing surface) and a second component part 502 (incorporating an outwardly facing surface). The interface between the first component part 501 and the second component part 502 has a flat planar shape (as shown in FIG. 4B), which is flat in all of the xz-, yz-, and xy-planes. A thin film (not shown) may be encapsulated between the first component part 501 and the second component part 502. Lamination on the planar interface between the first component part 501 and the second component part 502 is straightforward.

[0037] Finally, reference is made to Fig. 5B, which illustrates diagrammatically an assembled eyeglass lens 503 formed from the component parts of Fig. 5A. This shows how the first component part 501 and the second component part 502 combine to create the final eyeglass lens 503. It can be seen that the bond between the first component part 501 and the second component part 502 is away from the edge of the eyeglass lens 503 towards the center of the lens 503.

[0038] Thus, bisecting the same eyeglass lens by a flat intersection rather than a cylindrical interface means that the horizontal extent of the outer (outward facing) part is limited, as shown by eyeglass lens 503. This limits the possible size of the thin film that can be encapsulated in the eyeglass. Although it is possible to laminate a small area thin film on this surface and encapsulate it, it is preferable that any thin film encapsulated in the eyeglass extends close to the edge of the eyeglass lens. This prevents the edge from being seen and aids the lamination process. If a flat intersection is selected (as shown in Figures 4 and 5), but the size of the thin film is required to match the size of the eyeglass, this can be achieved by making the entire eyeglass thicker or by reducing the curvature profile. Thus, it can be seen that a cylindrical (curved) interface between the two component parts allows thinner laminates to be used, while also offering the greatest flexibility in the selection of the curvature profile. As a result, the final encapsulated eyeglass lens is thinner, lighter, cheaper and more consumer friendly than encapsulated eyeglass lenses made using different methods.

[0039] These advantages are further discussed by way of example with reference to Figure 6A which illustrates an example of a circular lens blank. This shows a 70mm diameter lens blank with an inner radius of curvature of 250mm, a thickness of 2.6mm, and an outer radius of curvature of 252.6mm (hence a perfectly concentric surface).

[0040] Referring now to FIG. 6B, an exploded view of the lens blank of FIG. 6A is illustrated bisected according to a planar interface. Bisecting the lens blank into two component parts with planar interfaces (e.g., as discussed with reference to FIGS. 4 and 5) results in a center thickness for each component part of 1.3 mm. As noted above, the planar intersection does not span the full extent of the 70 mm lens blank used in this example. In the resulting component, the outer outward facing part has a diameter of less than 70 mm. Thus, when depositing a thin film on the interface between the two parts, the size of the film is limited to the size of the outward facing component.

[0041] Referring now to FIG. 6C, an exploded view of the lens blank of FIG. 6A is illustrated bisected according to a cylindrically shaped interface. Bisecting using a cylindrical interface rather than a planar interface is also discussed with reference to FIGS. 2 and 3 above. Because the interface is flat in one axis (vertical), the outwardly facing components are limited to the same extent in one axis as the planar interface. However, they are no longer limited in the other (horizontal) axis. This is beneficial because, as shown with reference to FIGS. 2 and 3, most eyeglass components have an aspect ratio in which the horizontal axis is longer than the vertical axis.

[0042] 7, there is shown a schematic diagram of the relationship between radius of curvature and center thickness for a spherically shaped outwardly facing lens component size. Assuming a spherically curved outwardly facing component with radius of curvature R and center thickness T, the radius x of the outwardly facing component is given by the following equation: x = √R 2 -(RT) 2

[0043] It can thus be seen that the size of the outwardly facing component is limited by two factors: (1) the thickness of the lens, and (2) the radius of curvature of the outer surface. Fitting a larger membrane into the planar interface between the eye-facing component and the outwardly facing component would therefore mean making the lens thicker or decreasing the radius of curvature, both of which may be undesirable in an eyeglass frame for practical and / or aesthetic reasons.

[0044] In general terms and in a first aspect, a spectacle lens may be considered to comprise a first lens part attached to a second lens part with a cylindrically shaped interface therebetween, and a thin membrane interposed between the first and second lens parts at the cylindrically shaped interface. An optical device, such as an optical glass, a visual headset, or the like, comprising one or more spectacle lenses according to this aspect may also be considered.

[0045] In a second aspect, which may be combined with the first aspect, a method for producing a spectacle lens may be envisaged, the method comprising inserting a thin film between a first lens part and a second lens part at a cylindrically shaped interface between the first lens part and the second lens part. The resulting spectacle lens (which may have the first and second lens parts bonded together with the thin film inserted between them) may thus be according to the spectacle lens of the first aspect (as described above) or according to an intermediate product such as a spectacle lens blank from which a final spectacle lens may be formed.

[0046] According to either (or both) aspects, numerous optional and / or preferred features may be considered. For example, the spectacle lens may be generally elongated and / or have a (longer) major axis (typically horizontal) and a (shorter) minor axis (vertical). For example, the spectacle lens may be roughly trapezoidal (or rectangular), elliptical, or a shape between these two options. In any case, the cylindrically shaped interface preferably has a curved profile over the major axis of the spectacle lens. The cylindrically shaped interface then advantageously has a straight (or flat) profile over the minor axis. In certain embodiments, the spectacle lens has a spherical or spherocylindrical outer profile.

[0047] Advantageously, the first lens component has a first cylindrically shaped surface and the second lens component has a second cylindrically shaped surface which is then advantageously arranged to cooperate with the first cylindrically shaped surface to provide a cylindrically shaped interface.

[0048] Further generalized aspects will be considered below. First, more specific details according to embodiments will be considered.

[0049] As mentioned above, the thin film is typically a holographic optical element (HOE), which is an optical component that uses the principles of diffraction to generate holographic images and can be understood as a type of hologram. The HOE is typically recorded on a flat or planar surface. In this case, if the thin film is to be laminated or encapsulated in an eyeglass lens, the resulting HOE will have a curved profile, and corrections for this curvature and / or for the back (eye-facing) lens component part (which may refract the playback light before it hits the HOE) are built into the recording setup. By correcting for this curvature, the HOE will be correctly played back in its final curved state.

[0050] If the spectacle lens components described herein are, for example, components of suitable low birefringence plastic or glass, the HOE can preferably be recorded (in the dark) directly on the thin film when it is laminated onto one of the lens components (before or after encapsulation). No correction for the curvature of the spectacle lens or HOE is included in the recording, and the optimal optical performance of the HOE is maintained in any case. However, if the HOE is not fully encapsulated before recording (or the playback position may be changed afterwards), correction for the angle change introduced by the back (eye-facing) lens component part may still be desirable. Furthermore, it may be advantageous to avoid restacking of the thin film between recording and mounting (i.e. removing the film from a flat recording surface and restacking on a curved surface). This avoids restacking problems such as deregistration and avoids stresses imposed on the thin film. However, it is difficult to implement from a practical point of view.

[0051] Alignment of the optical system ensures that a high-quality (defect-free, high-resolution) virtual image is presented to the viewer. It is desirable, especially for augmented reality (AR) applications, to provide a precise alignment of the HOE. The optical center of the HOE is preferably aligned within the eyeglass lens, with an accuracy of + / - 0.1 mm relative to the optical axis of the projector or light source. Therefore, when the HOE needs to be removed from the flat surface (on which it was recorded) and re-laminate onto a curved surface for encapsulation within the eyeglasses, it is essential that the lamination be as easy as possible to allow for precise alignment of the HOE. The cylindrical inner surface described herein allows for easier lamination than a spherical inner surface, and therefore easier alignment. The HOE can alternatively be recorded on a reel-to-reel system and laminated in an automated process. Again, this procedure is easier on a cylindrical rather than a spherical surface.

[0052] The optical quality and stability of the HOE are also relevant for AR applications. Any variation in the HOE position or thickness will adversely affect the quality of the virtual image. The HOE is an optical element, which is typically specified to an accuracy of one wavelength or less. This indicates that if the HOE varies from its nominal position by more than one wavelength of light, the image will be affected. This variation may occur, for example, if lamination on a spherical surface causes wrinkles or stresses in the HOE. The surface to which the hologram is laminated is desirably of optical quality smoothness, positional stability, and known curvature, and the hologram desirably remains consistent with the surface after encapsulation for optimal image quality. Note that some existing methods for laminating films within glasses (e.g., cellulose acetate films for laminated safety glasses, photochromic films for sunglasses) do not require concern for precise positional accuracy when laminating because the films are primarily isotropic (i.e., the same in all positions / orientations).

[0053] Returning to the generalized aspect above, further details can be considered. Beneficially, the thin film comprises a holographic optical element. Preferably, the thin film is predominantly or mostly anisotropic (i.e. non-uniform in all, or at least most or the majority of positions / orientations).

[0054] In some embodiments, the holographic optical element is configured to act as a plane mirror. In this case, the holographic optical element may not exert any refractive power on its own. The total refractive power of the HOE may then be determined by the cylindrical curvature of the inner surface to which the HOE is laminated. A spectacle lens exhibits a real-world refractive power as determined only by the curvatures of the inner and outer surfaces of the spectacle lens.

[0055] Alternatively, the spectacle lens may be constructed such that the total refractive power of the HOE is determined by the sum of the refractive power of the hologram of the HOE and the refractive power due to the curvature of the cylindrically shaped interface. The HOE may then act as a reflective optical element (as is typical for AR applications).

[0056] In some embodiments, the thin film includes a photosensitive material. A hologram can then be recorded on the photosensitive material to form a holographic optical element. In certain cases, recording a hologram on the photosensitive material can include providing the photosensitive material on a planar substrate and recording a hologram on the photosensitive material when on the planar substrate, where the hologram is recorded to correct the refractive power of the cylindrically shaped interface. This may thereby provide a holographic optical element, which can then be applied to the cylindrically shaped interface. In other cases, recording a hologram on the photosensitive material can include applying the photosensitive material to the cylindrically shaped interface and recording a hologram on the photosensitive material when on the cylindrically shaped interface.

[0057] While specific embodiments have been described herein, those skilled in the art will recognize that various modifications and variations are possible. Of course, it should be understood that variations to design distances, dimensions, curvatures, angles, and component sizes are possible without changing the underlying disclosure. Also, additional optical components can be incorporated to redirect and / or process light, as desired.

[0058] Although it is preferred that the curved cylindrical shape is across the major (horizontal) axis and the interface profile is straight across the minor (vertical) axis, it may be possible to implement the techniques according to the present disclosure with a curved cylindrical shape across the minor (vertical) axis and a straight interface profile across the major (horizontal) axis. The curved cylindrical shape may also be at an angle, for example 45 degrees, to the major and minor axes of the spectacle lens component shape.

[0059] In some applications, it may be possible for the interface between two spectacle lens components to be curved in two axes. However, in this case, the curvature of the interface in the short axis or the vertical axis is minimized, and the ideal curvature is zero. In other words, any deviation from a non-zero curvature in the short axis is negligible. Any curved shape (e.g., over the long axis) is possible.

[0060] A typical HOE in an AR system is a reflective hologram. However, a transmission HOE can be used instead or as well. Transmission AR applications are known in practice. A transmission HOE may have refractive power in some cases, but alternatively it does not have refractive power and therefore can be called a planar transmission element or a hologram (transmission equivalent to a planar mirror).

[0061] The outer shape (profile) of the spectacle lens is preferably spherical or spherocylindrical, but in some embodiments can be toric or aspherical, as such shapes are less common and are generally more expensive to manufacture.

[0062] The manufacturing process described above first forms two lens component parts and then encapsulates a thin film (HOE) between them. However, these steps may be integrated, in particular the thin film (HOE, or the photosensitive material from which the HOE may be formed) may be formed integrally with the first lens component or the second lens component. The lens components are advantageously formed such that the thin film is located at the interface. For example, this may be achieved if at least one of the lens component parts is formed by injection molding. The thin film may then be incorporated into the casting process when making any of the component parts. The thin film is positioned so that it is on the cylindrical side of the mold for the lens component (interface). Resin is then injected and the film is bonded to the component via casting (not by lamination). As a result, two lens components may be formed, but one already has a thin film fused on the interface.

[0063] In relation to the generalization above, for example, further options may be considered. For example, the thin film may be formed integrally with the first lens component or the second lens component in an embodiment. One of the lens components may be considered to have an eye-facing surface (opposite the cylindrical interface surface). This may be formed in any shape. After bonding the two lens components with the thin film encapsulated between them, the resulting product may be considered as a spectacle lens blank. The eye-facing surface of the spectacle lens blank may be milled to form a spectacle lens.

[0064] The eyeglass lens (or lenses) according to the present disclosure may typically be used for AR applications. Applications other than AR may include eye tracking and reflective filters for certain wavelengths of light (e.g., some infrared or laser light to avoid distraction or damage). It may be possible (but more difficult) to use the eyeglass lens(es) according to the present disclosure for virtual reality (VR) applications as well.

Claims

1. A spectacle lens, a first lens component attached to a second lens component with a cylindrically shaped interface therebetween; a thin film interposed between the first lens component and the second lens component at the cylindrically shaped interface.

2. The eyeglass lens of claim 1 , wherein the eyeglass lens has a major axis and a minor axis, and the cylindrically shaped boundary surface has a curved profile across the major axis.

3. The spectacle lens of claim 2 , wherein the cylindrically shaped interface has a straight profile across the minor axis.

4. 10. A spectacle lens according to any preceding claim, wherein the thin film comprises a holographic optical element and / or the thin film is anisotropic.

5. 5. The spectacle lens of claim 4, wherein the holographic optical element is configured to act as a plane mirror or a plane transmission hologram.

6. 5. The spectacle lens of claim 4, wherein the spectacle lens is configured such that the total refractive power of the holographic optical element is determined by the sum of the refractive power of the ahologram of the holographic optical element and the refractive power due to the curvature of the cylindrically shaped boundary surface.

7. 10. A spectacle lens according to any of the preceding claims, wherein the spectacle lens has a spherical or spherocylindrical outer profile.

8. 1. A method for manufacturing a spectacle lens, comprising the steps of: A method comprising: interposing a thin film between a first lens component and a second lens component at a cylindrically shaped interface between the first component and the second component.

9. 9. The method of claim 8, wherein the first lens component has a first cylindrically shaped surface and the second lens component has a second cylindrically shaped surface, the second cylindrically shaped surface being arranged to cooperate with the first cylindrically shaped surface to provide the cylindrically shaped boundary surface.

10. 10. The method of claim 8 or 9, wherein the spectacle lens as a major axis and a minor axis, the cylindrically shaped boundary surface has a curved profile across the major axis.

11. The method of claim 10 , wherein the cylindrically shaped boundary surface has a linear profile across the minor axis.

12. The method of any one of claims 8 to 11, wherein the thin film comprises a holographic optical element.

13. The method of claim 12 , wherein the holographic optical element is configured to act as a plane mirror or a plane transmission hologram.

14. the thin film comprises a photosensitive material, and the method further comprises: The method of any one of claims 8 to 11, further comprising recording a hologram on the photosensitive material to form a holographic optical element.

15. said step of recording a hologram on said photosensitive material further comprising: applying said photosensitive material to said cylindrically shaped interface; and recording the hologram on the photosensitive material when on the cylindrically shaped interface.

16. said step of recording a hologram on said photosensitive material further comprising: providing the photosensitive material on a planar substrate; 15. The method of claim 14, comprising: recording the hologram on the photosensitive material when it is on the planar substrate, the hologram being recorded to correct for the refractive power of the cylindrically shaped interface.

17. The method of any one of claims 8 to 15, wherein the thin film is integrally formed with the first lens component or the second lens component.

18. bonding the first lens component and the second lens component with the interposed membrane to form an eyeglass lens blank; The method according to any one of claims 8 to 17, further comprising milling an eye-facing surface of the spectacle lens blank.

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