Thin film encapsulation within spectacle lenses

Abstract

The present disclosure relates to a spectacle lens comprising: a first lens portion affixed to a second lens portion, with a cylindrical interface between the first lens portion and the second lens portion; and a film interposed between the first lens portion and the second lens portion at the cylindrical interface. The present disclosure also relates to a method of manufacturing an ophthalmic lens comprising interposing a film between a first lens portion and a second lens portion at a cylindrical interface between the first portion and the second portion.

Description

[0001] This application is a divisional application of a patent application with application number 202280013688X, application date February 28, 2022, and invention name “Thin film packaging in eyeglass lenses”. Technical Field

[0002] The present disclosure relates to eyeglass lenses with encapsulation films and lens manufacturing and / or thin film encapsulation technology for producing eyeglass lenses with encapsulation films. Background Art

[0003] Eyeglass lenses are usually manufactured by lens grinding or injection molding techniques. The injection molding process of eyeglass lenses consists of injecting molten material into a mold under high pressure. The shape of the mold is either the blank shape (producing a lens 'blank' with the purpose of further shaping the inner surface to produce the final lens), or the exact contour of the desired eyeglass lens, including the inner curvature profile and the outer curvature profile. After a short cooling, the lens is completed. Due to the ease and speed of this process, injection molding is the preferred technology for large quantities and stock lenses such as sunglasses. For more customized applications, lens grinding technology is favored. The lens grinding process starts with a lens 'blank', which has a convex outer (world-facing) surface and a flat or concave eye-facing surface. The profile of one or more curved surfaces of these blanks is usually spherical or spherocylindrical. Specialized machinery is then used to grind the inner surface to the desired curvature profile and polish it. The eyeglass lens is then edged to the desired edge profile to fit in the frame, and the glasses are completed. With the advent of 3D printing (or additive manufacturing) technology, it is also possible to 3D print eyeglass lenses with completely customized curvature and edge profiles.

[0004] Laminating thin films onto eyeglass lenses or encapsulating the thin films within eyeglass lenses is desirable for many purposes. For example, the augmented reality (AR) industry (including eye tracking applications) desires holographic optical elements (HOEs) that can be produced on thin polymer films and then attached to or encapsulated within eyeglass lenses.

[0005] There are existing methods for encapsulating films within or laminating films onto glasses. For example, US-2015 / 0131047A1 details a process for laminating cellulose acetate laminate films directly onto glasses of different profiles for use in safety glass. US-2017 / 0068095A1 describes many techniques. In the first of these techniques, the lens is injection molded, whereby a mold with a cavity is made to place the HOE photopolymer film before casting. The eyeglass material is then injected into the mold, encapsulating the HOE therein. The second technique encapsulates the HOE between two half-lenses, 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 method, the photopolymer film is laminated directly to the concave inner surface of the eyeglass lens.

[0006] Known methods involve either complex manufacturing techniques or the risk of deformation and / or delamination of the film. Therefore, a less complex manufacturing technique is desired to integrate the film with an eyeglass lens without such significant difficulties. Summary of the invention

[0007] Against this background, a spectacle lens according to claim 1 and a method for manufacturing a spectacle lens according to claim 8 are provided. A technique for producing a spectacle lens with an encapsulation film and the resulting spectacle lens with an encapsulation film are provided, whereby stresses and deformations are minimized. This is achieved by providing a film on a cylindrical interface between two parts of the spectacle lens.

[0008] It has been found that when the film is packaged in a lens, many stresses and deformations are induced by lamination on curved surfaces and especially surfaces that are curved across two axes, as is the case with conventional eyeglass lenses. Laminating a film directly onto a surface with spherical curvature (or other curvature profiles across two axes, which are typically chosen for minimum thickness) can create elastic stresses in the film, leading to deformation and delamination.

[0009] In contrast, it has been found that such stresses are avoided when the film is laminated onto a cylindrical surface. For completeness, it should be noted that a cylindrical surface means that the surface has the shape of a portion of a cylinder along its axis of elongation. In other words, the surface is curved along one dimension (e.g. circular or elliptical), but is straight (or flat) along the vertical dimension. A cylindrical interface is highly unconventional, in particular because it does not conform to the shape of an eyeglass lens and is therefore considered non-compact. However, the cylindrical interface can still provide a low thickness without difficulty when laminating.

[0010] Thus, the spectacle lens can be produced using two component parts with a thin film encapsulated between the two component parts. Thus, the lens can be produced using two components: a rear (eye-facing) part; and a front (world-facing) part. The interface between the two components has the cylindrical shape discussed above. In other words, taking a cross section along a plane, preferably a plane parallel to the major axis (usually horizontal), shows the interface as curved (e.g., a circular or elliptical segment). A cross section along a vertical plane, typically parallel to the minor axis (usually vertical), is preferably flat or straight. Limiting the curvature on the minor axis (preferably to zero) allows the thinnest stacking and imposes the least restrictions on the choice of inner and outer curvatures.

[0011] In simple cases, lenses with a spherical or sphero-cylindrical outer profile (typically used for normal prescription eyeglass lenses) can be split or formed into two component parts, where the interface between the two parts has a cylindrical profile. Laminating a thin layer onto a cylindrical surface causes a low risk of deformation and delamination. Since this surface has a curvature in only one axis, it does not produce the same stresses on the film compared to lamination on a spherical surface.

[0012] The two parts can be manufactured by any technology, for example: injection molding technology, which is usually used for mass production; grinding and polishing technology, which is usually used for more customized requirements; or 3D printing. Optionally, the film can be integrated with one of the lens parts (so as to be located at the formed interface), for example by placing the film in the mold before casting. After combining the two lens parts with the film inserted between the two lens parts (regardless of whether any lens part is formed integrally with the film), the resulting eyeglass lens can be considered as a blank. The surface of the blank facing the eye can then be milled to form the eyeglass lens.

[0013] Typical spectacles are meniscus lenses, meaning that the surface facing the eye is concave and the surface facing the world is convex. Typical spectacles will also exhibit a certain aspect ratio (thus defining a major axis and a minor axis), whereby the horizontal extent of the lens (major axis) is greater than the vertical extent (minor axis). This aspect ratio advantageously allows the spectacles lens to be bisected into two components for the purpose of encapsulating the thin film.

[0014] The film is preferably non-isotropic. Typically, the film comprises a holographic optical element (HOE), which can act as a reflective or transmissive element. In some embodiments, the HOE can act as a plane mirror or a plane transmission hologram in the absence of optical power. Alternatively, the HOE can add optical power so that the total optical power of the HOE is the sum of the optical power of the hologram and the optical power generated due to the curvature of the cylindrical interface.

[0015] The 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 a cylindrical interface. In such cases, 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 such cases, no additional compensation for the cylindrical interface is required.

[0016] Combinations of various aspects or features from various aspects are also conceivable, where such combinations are feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present disclosure may be implemented in many ways and a preferred embodiment will now be described by way of example only and with reference to the accompanying drawings, in which:

[0018] FIG1 shows a perspective view of a conventional eyeglass lens;

[0019] Figure 2A depicts a perspective view of an eyeglass lens according to the present disclosure;

[0020] Figure 2B Shown through Figure 2A A cross-sectional view of a spectacle lens;

[0021] Figure 3A Depicted Figure 2A Component parts of eyeglass lenses;

[0022] Figure 3B Schematically shows Figure 3A The assembly form of the component parts;

[0023] Figure 4A A perspective view of an example alternative eyeglass lens is shown;

[0024] Figure 4B Shown through Figure 4A A cross-sectional view of a spectacle lens;

[0025] Figure 5A Depicted Figure 4A Component parts of eyeglass lenses;

[0026] Figure 5B Schematically shows Figure 5A The assembly form of the component parts;

[0027] Fig. 6A An example circular lens blank is depicted;

[0028] Figure 6B Shows the bisection of the plane interface Fig. 6A An exploded view of a lens blank;

[0029] Figure 6C Shows the bisection of the cylindrical interface Fig. 6A an exploded view of the lens blank; and

[0030] Figure 7 The relationship between the radius of curvature and the center thickness on the world-facing lens component of a certain size is schematically shown.

[0031] The drawings are schematic in nature and exact dimensions and configurations should not be inferred unless explicitly shown or described. DETAILED DESCRIPTION

[0032] Referring first to FIG. 1 , a perspective view of an existing spectacle lens 101 is shown having an eye-facing surface 102 and a world-facing surface 103. This is a simple zero-power spherical lens (like the other spectacle lenses shown in the drawings) and is for illustration purposes only. It will be appreciated that embodiments may be applied to other spectacle lenses, including prescription spectacle lenses and spectacle lenses with different curved profiles.

[0033] Common glasses are meniscus lenses, which means that the surface 102 facing the eye is concave, and the surface 103 facing the world is convex. As mentioned above, the spectacle lens 101 shown has a spherical radius of curvature on both the inner and outer surfaces. Simple spherical lenses are commonly used for zero-power stock lenses for applications including sunglasses and ski goggles. In this application, both the front surface and the rear surface have a spherical curvature, where the two curvature profiles are concentric. For prescription lenses, cylindrical power is usually added to the rear lens surface 102 to correct astigmatism. However, the surface is usually spherical cylindrical (as described in "Principles of Ophthalmic Lenses", M Jalie, Association of British Dispensing Opticians College of Education). The usual size of the spectacle lens is shown for illustration only.

[0034] Also shown in Figure 1 are axes, which will be used consistently in other figures of the present 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, typically by at least a factor of 10) compared to the size of the other dimensions.

[0035] The outer (world-facing) surface of an eyeglass lens typically has a spherical curvature, which is often referred to as the "base curvature". This base curvature has the functional purpose of providing the best optical performance of the lens, while also serving to improve the aesthetics of the lens and reduce the weight of the lens. A 6 diopter curved front surface (equivalent to approximately an 83mm radius of curvature) is considered the 'optimum form' for providing the best peripheral vision (based on empirical data). For aesthetic reasons, reading glasses and fashion lenses typically have a slightly flatter surface, with a 4 diopter base curve being common.

[0036] For additional information (but again, not specifically limiting), it should be noted that the illustrated spectacle lens 101 has a lens horizontal extent (along the x-axis) of 55 mm and a lens vertical extent (along the y-axis) of 32 mm. The lens has a uniform thickness of 2 mm with an inner (facing the eye) radius of curvature of 150 mm (approximately 3.3 diopters) and an outer (facing the world) radius of curvature of 152 mm. This is a typical zero-power stock lens, but as mentioned above, 6 diopters or 4 diopters lenses may be more common. Prescription lenses will have different thickness profiles.

[0037] Reference now Figure 2A , which depicts a perspective view of an eyeglass lens 201 according to the present disclosure. According to the present disclosure, a thin film is encapsulated in an eyeglass lens by forming the eyeglass lens into two parts, wherein the interface between the two parts is a cylindrical profile. The parameters of the thin film are generally well understood, but in this context, the thickness of the film can be about 100 microns or less. The thin film is typically a low absorption, optically clear (or transparent) low haze film suitable for incorporation into a lens without significantly affecting perspective. A reference plane 202 at the center of the eyeglass lens is highlighted in the xz plane. Also refer to Figure 2B , which shows the passage through the reference plane 202 Figure 2A Here, the cylindrical interface contour 203 between the two component parts is shown in dashed lines.

[0038] The two component parts are typically manufactured separately, but can optionally be formed from separate eyeglass lenses. Cylindrical surfaces on lenses or lens components are not common. The cylindrical surface between the two lens components can be made by grinding or custom molds (injection molding). Optionally, 3D printing can be used to manufacture the lens components. Manufacturing lens components with cylindrical interfaces is not a standard technology. However, injection molding (e.g. plastic), grinding or 3D printing can be used. Standard lens grinding and mold manufacturing can use diamond turning, which usually means spherical surfaces, but cylindrical surfaces can be achieved using this and other techniques.

[0039] Next reference Figure 3A , depicting Figure 2A The component parts of the eyeglass lens are as follows. The component parts include: a first component part (incorporating the surface facing the eye) 301; and a second component part (incorporating the surface facing the world) 302. The interface between the first component part 301 and the second component part 302 has a cylindrical shape (e.g. Figure 2B ), the interface is curved in the xz plane (in this case a circle segment) and is flat in the yz plane (and also flat in the xy plane).

[0040] In this example, the cylindrical shape is curved in the x-axis, particularly with a radius of curvature of 151 mm, and the profile is flat in the y-axis. It can thus be seen that the use of a purely cylindrical interface between the two parts allows the formation of two components, each having a component size of 55 mm (x) x 32 mm (y) (i.e., the major and minor axes of the spectacle lens are the same size), which are combined to make the final spectacle lens. The center thickness of each component is approximately 1.3 mm.

[0041] A film with the same size and profile as the glasses (55 mm in the x-direction and 32 mm in the y-direction) Figure 3A The film is preferably laminated on a cylindrical interface between the first component part 301 and the second component part 302 (not shown in the figure). When the first component part 301 and the second component part 302 are then attached to each other, the film is completely encapsulated within the eyeglass lens. Lamination on a cylindrical surface avoids deformations associated with lamination on a spherical surface. The interface is preferably a pure cylinder, but can also be a partial spherical cylinder or a complex surface, as long as any deviation from the pure cylindrical shape is negligible. The closer the interface is to a perfect cylinder, the less stress there is in the film. The film is preferably a holographic optical element (HOE) or a photosensitive material suitable for recording a HOE therein.

[0042] As described above, the cylindrical interface between the first component portion 301 and the second component portion 302 is flat in one axis. Therefore, the cylindrical interface exhibits the same geometric limitations in this axis as using a flat film. However, since spectacle lenses typically have a significant aspect ratio, this limitation becomes less important if it only applies to the shorter (minor) axis of the spectacle lens, as will now be discussed further below.

[0043] The film can be attached to the cylindrical surface of one of the lens components in a variety of ways. The lamination of the film may not require the film to be adhered to one or both surfaces of the cylindrical interface (the first component part 301 and the second component part 302 can be simply attached to each other with the film between the first component part and the second component part), but additional adhesion can be provided. The HOE can be a photopolymer, such as Bayfol (RTM) HX (sold by Covestro AG), which typically has a substrate of about 60 microns thick and a polymer layer of about 20 microns thick. Then, one side of the photopolymer is usually a sticky film, which will adhere to glass or plastic once laminated to the surface using a roller (or the like). Alternatively or additionally, glue, double-sided tape, vacuum treatment, heat treatment or pressure treatment can be used to adhere the HOE to the substrate. The HOE can alternatively be a silver halide film, and the above-mentioned technology can also be used to adhere the film to the substrate surface. The choice of lens material helps to improve adhesion, for example, polycarbonate can provide better adhesion. The film will not usually extend all the way to the edge of the cylindrical interface. This can result in a better package (no moisture ingress) if there is a good glue seal all around.

[0044] refer to Figure 3B , schematically showing Figure 3A Assembled eyeglass lens 303 of component parts. Also shown is a film 304 encapsulated between the first component part 301 and the second component part 302. Thus, the completed eyeglass lens 303 is formed by two component parts mated together by a cylindrical interface, with the film 304 interposed between the components.

[0045] The eye-facing component (first component part 301) can be molded in the desired shape of the spectacle lens. More typically, the eye-facing component is molded as a lens blank, where the component will have a cylindrical profile on the front surface (to be bonded to the world-facing component 302), but the back surface can be flat or have some arbitrary surface curvature. The first component part 301, the second component part 302 and the film 304 are then bonded to form the spectacle lens 303 as a lens 'blank' with an embedded HOE.

[0046] Once the assembled eyeglass lens 303 is formed in this manner, it will appear as a rounded profile lens blank, and the rear surface can be ground to a standard lens blank to produce the final lens. In order to fit the eyeglasses, the front and rear curvatures are usually edged (grinded around the edges) to fit the eyeglass frame. This treatment can be performed on the first component part 301 and the second component part 302 before film packaging and assembly or after assembly. When the front surface and / or the rear surface are ground to a certain curvature, the grinding process is a more intensive process than edging, and if necessary, it is preferred that this process be performed on the first component part 301 and / or the second component part 302 before packaging the film and assembly.

[0047] Thus, the world-facing component is typically formed to include a front surface that is typically spherical with a desired base curvature and a rear surface with a cylindrical profile. The eye-facing component may be formed to include a front surface and a rear surface with a cylindrical profile. The rear surface may then be formed to have the curvature desired for the final prescription. Alternatively, the rear surface may remain flat (or have an arbitrary curvature) to produce a lens blank, whereby further grinding of this surface will be used to set the prescription.

[0048] Reference now Figure 4A , shows a perspective view of an example alternative spectacle lens 401. This alternative spectacle lens 401 does not have a cylindrical interface between the two lens components, but a planar interface. This is shown for comparison purposes. A reference plane 402 in the center of the spectacle lens is highlighted in the xz plane. Also refer to Figure 4B , which shows the passage through the reference plane 402 Figure 4A Here, the planar (flat) interface contour 403 between the two component parts is shown in dashed lines.

[0049] Reference now Figure 5A , depicting Figure 4A The component parts of the eyeglass lens are as follows. The component parts include: a first component part (incorporating the surface facing the eye) 501; and a second component part (incorporating the surface facing the world) 502. The interface between the first component part 501 and the second component part 502 has a flat, planar shape (such as Figure 4B 501 and 502. The shape is flat in all xz, yz and xy planes. A thin film (not shown) may be encapsulated between the first component portion 501 and the second component portion 502. Lamination on the planar interface between the first component portion 501 and the second component portion 502 is simple.

[0050] Finally, reference Figure 5B , which schematically shows the Figure 5AThis shows how the first component part 501 and the second component part 502 are combined to produce the final spectacle lens 503. It can be seen that the joint between the first component part 501 and the second component part 502 is away from the edge of the spectacle lens 503 towards the center of the lens 503.

[0051] Therefore, bisecting the same eyeglass lens by a flat intersection rather than a cylindrical interface means that the horizontal extent of the outer (world-facing) portion is limited, as shown in eyeglass lens 503. This limits the possible size of the film that can be packaged in the eyeglasses. Although a small area of ​​film can be laminated and packaged on this surface, any film packaged in the eyeglasses preferably extends to the edge close to the eyeglass lens. This can prevent visible edges and help the lamination process. If a plane intersection is selected (as shown in Figures 4 and 5), the size of the film needs to match the size of the eyeglasses, which can be achieved by making the entire eyeglasses thicker or by reducing the curvature profile. Therefore, it can be seen that the cylindrical (curved) interface between the two component parts allows the use of thinner stacking while also providing maximum flexibility in the choice of curvature profile. Therefore, the final packaged eyeglass lens is thinner, lighter, cheaper and more consumer-friendly than the packaged eyeglass lens manufactured using a different method.

[0052] These benefits will refer to Fig. 6A , which depicts an exemplary circular lens blank. This shows a lens blank of 70 mm diameter, with an inner radius of curvature of 250 mm, a thickness of 2.6 mm, and an outer radius of curvature of 252.6 mm (thus being completely concentric surfaces).

[0053] Next reference Figure 6B , showing the bisection of the plane interface Fig. 6A Exploded view of a lens blank of FIG. 4. The lens blank is bisected into two component parts with a planar interface (e.g., as discussed with reference to FIGS. 4 and 5), resulting in a center thickness of 1.3 mm for each component part. As discussed above, the planar intersection does not reach the full extent of the 70 mm lens blank used in this example. In the resulting component, the diameter of the part facing the outside world is less than 70 mm. Therefore, if a thin film is to be laminated at the interface between the two parts, the size of the film is limited to the size of the part facing the world.

[0054] Reference now Figure 6C , showing the bisection of the cylindrical interface Fig. 6AExploded view of a lens blank of FIG. The use of a cylindrical rather than a planar interface for bisection is also discussed with reference to FIGS. 2 and 3 above. Since the interface is flat in one axis (vertical), the world-facing component is constrained in one axis to the same degree as a planar interface. However, the world-facing component is no longer constrained in the other (horizontal) axis. This is beneficial because most eyeglass components have an aspect ratio whereby the horizontal axis is longer than the vertical axis, as shown with reference to FIGS. 2 and 3.

[0055] Reference now Figure 7 , schematically illustrates the relationship between the radius of curvature and the center thickness on a lens component of a certain size. Assuming a spherically curved world-facing component with a radius of curvature R and a center thickness T, the radius x of the world-facing component is given by the following expression:

[0056]

[0057] Thus, it can be seen that the size of the world-facing component is limited by two factors: (1) thickness on the lens; and (2) radius of curvature of the outer surface. Thus, fitting a larger film in the planar interface between the eye-facing and world-facing components means either making the lens thicker or reducing the radius of curvature. Both of these situations may be undesirable for eyeglass frames for practical and / or aesthetic reasons.

[0058] In general and in a first aspect, a spectacle lens may be considered, comprising: a first lens portion attached to a second lens portion with a cylindrical interface between the first lens portion and the second lens portion; and a film interposed between the first lens portion and the second lens portion at the cylindrical interface. An optical device, such as optical glass, visual headphones or the like, may also be considered, comprising one or more spectacle lenses according to this aspect.

[0059] In a second aspect that may be combined with the first aspect, a method of manufacturing a spectacle lens may be contemplated. The method comprises inserting a film between the first lens portion and the second lens portion at a cylindrical interface between the first lens portion and the second lens portion. Thus, the resulting spectacle lens (which may involve the first lens portion and the second lens portion combined with the film inserted therebetween) may be a spectacle lens according to the first aspect (as discussed above) or an intermediate product, such as a spectacle lens blank, from which a final spectacle lens may be formed.

[0060] According to either (or both) aspects, a number of optional and / or preferred features may be considered. For example, the spectacle lens may be generally elongated and / or may have a (longer) major axis (generally horizontal) and a (shorter) minor axis (vertical). For example, the spectacle lens may be generally trapezoidal (or rectangular), elliptical, or a shape between these two options. In any case, the cylindrical interface preferably has a curved profile across the major axis of the spectacle lens. The cylindrical interface then advantageously has a straight (or flat) profile across the minor axis. In certain embodiments, the spectacle lens has a spherical or spherocylindrical outer profile.

[0061] Advantageously, the first lens portion has a first cylindrical surface and the second lens portion has a second cylindrical surface.The second cylindrical surface is then advantageously arranged to cooperate with the first cylindrical surface to provide a cylindrical interface.

[0062] Further generalized aspects will be discussed below.First, more specific details according to embodiments will be considered.

[0063] As mentioned above, the film is typically a holographic optical element (HOE), which is an optical component that uses the principles of diffraction to produce a holographic image 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 film is to be laminated or encapsulated into an eyeglass lens, whereby the resulting HOE has a curved profile, compensation for this curvature and / or the portion of the rear (eye-facing) lens component that may refract the replay light before it reaches the HOE is incorporated into the recording setup. By compensating for this curvature, the HOE will be correctly replayed in its final curved state.

[0064] For example, if the eyeglass lens components as described herein have suitable low birefringence plastic or glass, the HOE can preferably be recorded directly (in the dark) on the film when the film is laminated onto one of the lens components (before or after encapsulation). No compensation for the curvature of the eyeglass lens or the 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 subsequently), compensation for the angle changes introduced by the rear (facing the eye) lens component may still be desired. In addition, it may be advantageous to avoid re-lamination of the film between recording and implementation (i.e., removing the film from the flat recording surface and re-laminating it onto the curved surface). This avoids re-lamination problems, such as de-registration, and avoids added stress on the film. However, from a practical point of view, implementation is difficult.

[0065] Alignment of the optical system is desirable, particularly for augmented reality (AR) applications, in order to provide the viewer with a high quality (aberration-free, high resolution) virtual image. The optical center of the HOE is desirably aligned within the eyeglass lens, preferably with an accuracy of + / -0.1 mm relative to the optical axis of the projector or light source. Therefore, if the HOE needs to be removed from a planar surface (on which the HOE is recorded) and re-laminated on a curved surface to be packaged within the eyeglasses, it is critical that the lamination is as easy as possible to allow precise alignment of the HOE. The cylindrical inner surface described herein allows easier lamination and therefore easier alignment than a spherical inner surface. The HOE can alternatively be recorded on a roll-to-roll system and laminated in an automated process. Again, this procedure is simpler on a cylindrical surface than on a spherical surface.

[0066] The optical quality and stability of the HOE are also relevant to AR applications. Any change in the position or thickness of the HOE will negatively affect the quality of the virtual image. The HOE is an optical element, and the accuracy of optical elements is typically specified to 1 wavelength or less. This means that if the HOE varies from the nominal position by more than 1 wavelength of light, the image will be affected. For example, such a change may occur if lamination on a spherical surface causes wrinkles or stresses in the HOE. The surface onto which the hologram is laminated is expected to have optical quality smoothness, positional stability, and a known curvature, and the hologram is expected to remain conformal to the surface after packaging for optimal image quality. It should be noted that some existing methods for laminating thin films in glasses (e.g., cellulose acetate films for laminated safety glass, photochromic films for sunglasses) do not need to consider precise positional accuracy when laminating because the films are primarily isotropic (i.e., all positions / orientations are the same).

[0067] Returning to the general aspects discussed above, further details may be considered. Advantageously, the film comprises a holographic optical element. Preferably, the film is predominantly or mostly non-isotropic (ie, all or at least most or most positions / orientations are not the same).

[0068] In some embodiments, the holographic optical element is configured to act as a plane mirror. In this case, the holographic optical element itself may not add optical power. The total optical power of the HOE may then be determined by the cylindrical curvature of the inner surface to which the HOE is laminated. The eyeglass lens exhibits optical power in the real world as determined only by the inner and outer surface curvatures of the eyeglass lens.

[0069] Alternatively, the eyeglass lens may be configured such that the total optical power of the holographic optical element is determined by the sum of the optical power of the hologram of the holographic optical element and the optical power due to the curvature of the cylindrical interface. The HOE may then act as a reflective powered optical element (as is typically the case for AR applications).

[0070] In some embodiments, the film includes a photosensitive material. A hologram can then be recorded on the photosensitive material to form a holographic optical element. In some cases, recording a hologram on the photosensitive material may include: providing the photosensitive material on a planar substrate; and recording the hologram on the photosensitive material while on the planar substrate, the hologram being recorded to compensate for the optical power of the cylindrical interface. This can thereby provide a holographic optical element, which can then be applied to the cylindrical interface. In other cases, recording a hologram on the photosensitive material may include: applying the photosensitive material to the cylindrical interface; and recording the hologram on the photosensitive material while on the cylindrical interface.

[0071] Although specific embodiments have now been described, those skilled in the art will appreciate that various modifications and variations are possible. It should of course be understood that variations in design distances, dimensions, curvatures, angles, and component sizes are possible without changing the basic disclosure. Moreover, additional optical components may be incorporated to redirect and / or process light as desired.

[0072] Although it is preferred that the curved cylindrical shape spans the long (horizontal) axis and the interface profile is straight across the short (vertical) axis, the method according to the present disclosure can be implemented with a curved cylindrical shape across the short (vertical) axis and an interface profile straight across the long (horizontal) axis. Moreover, the curved cylindrical shape can be at an angle, such as 45 degrees, to the long and short axes of the eyeglass lens component shape.

[0073] In some applications, the interface between two eyeglass lens components can be curved in two axes. However, in this case, the curvature of the interface in the minor or vertical axis is minimized, where the ideal curvature is zero. In other words, any deviation from non-zero curvature in the minor axis is negligible. Any curved shape (e.g., across the major axis) is possible.

[0074] The usual HOE in an AR system is a reflective hologram. However, a transmissive HOE may be used instead or in conjunction. Transmissive AR applications are well known in practice. A transmissive HOE may have optical power in some cases, but may alternatively have no optical power and may then be referred to as a planar transmissive element or hologram (the transmissive equivalent of a plane mirror).

[0075] The outer shape (contour) of the eyeglass lens is preferably spherical or spherocylindrical, but may be toric or aspherical in some embodiments. Such shapes are less common and are generally more expensive to manufacture.

[0076] The manufacturing process discussed above first forms two lens component parts and then encapsulates the film (HOE) between the two lens component parts. However, these steps can be integrated, and in particular, the film (HOE or photosensitive material that can form the HOE) can be formed integrally with the first lens part or the second lens part. The lens parts are advantageously formed so that the film is located at the interface. For example, this can be achieved if at least one of the lens component parts is formed by injection molding. The film can then be incorporated into the casting process when any of the component parts is produced. The film is placed so that it rests against the cylindrical side (interface) of the lens component mold. The resin is then injected and the film is bonded to the component by casting (rather than lamination). As a result, two lens components can be formed, but one lens component will already have the film fused to it at the interface.

[0077] For example, with respect to the general terms discussed above, further options may be considered. For example, in an embodiment, the film may be integrally formed with the first lens portion or the second lens portion. One of the lens components may be considered to have a surface facing the eye (as opposed to a cylindrical interface surface). This may be formed into any shape. After combining the two lens portions with the film encapsulated between the two lens portions, the resulting product may be considered to be a spectacle lens blank. The surface of the spectacle lens blank facing the eye may be milled to form a spectacle lens.

[0078] The eyeglass lens (or lenses) according to the present disclosure may be used generally for AR applications. Applications other than AR may include eye tracking and reflective filters for specific wavelengths of light (e.g. some infrared light or lasers to avoid interference or damage). It is also possible (but more difficult) to use the eyeglass lenses according to the present disclosure for virtual reality (VR) applications.

Claims

1. A method of manufacturing a spectacle lens for augmented reality glasses, the method comprising the following steps: forming a first lens portion, the first lens portion comprising a cylindrical surface and an eye-facing surface; applying a film to the cylindrical surface; forming a second lens portion and applying the second lens portion over the cylindrical surface and the film such that the film is interposed between the first lens portion and the second lens portion at a cylindrical interface between the first lens portion and the second lens portion, Wherein the film is a holographic optical element, the holographic optical element is recorded to compensate for the optical power of the cylindrical surface.

2. The method of claim 1, wherein the holographic optical element is recorded to compensate for the curvature of the cylindrical surface.

3. The method of claim 1 or 2, wherein the first lens portion is formed by injection molding.

4. The method according to claims 1 to 3, wherein the second lens portion is formed by casting.

5. A method according to claims 1 to 4, wherein after casting on the first lens part, the second lens part includes a cylindrical surface, and the cylindrical surface of the second lens part is arranged to cooperate with the cylindrical surface of the first lens part to provide the cylindrical interface.

6. The method of claims 1 to 5, comprising a major axis and a minor axis, the cylindrical interface having a curved profile across the major axis.

7. The method of claims 1 to 6, wherein the cylindrical interface has a straight profile across the minor axis.

8. The method of any one of claims 1 to 7, wherein the thin film comprises a photosensitive material.

9. The method according to any one of claims 1 to 8, further comprising: combining the first lens portion and the second lens portion with the interposed film to form an eyeglass lens blank; The surface of the spectacle lens blank facing the eye is ground.

10. A spectacle lens for augmented reality glasses, the spectacle lens comprising: a first lens portion, the first lens portion comprising a cylindrical surface and an eye-facing surface, the first lens portion being attached to a second lens portion with a cylindrical interface therebetween; and A film is interposed between the first lens portion and the second lens portion at the cylindrical interface, wherein the film comprises a holographic optical element recorded to compensate for the optical power of the cylindrical surface.

11. An eyeglass lens according to claim 10, wherein the holographic optical element is recorded to compensate the optical power of the eye-facing surface of the first lens part.

12. The spectacle lens according to claim 10 or 11, wherein the holographic optical element is recorded to compensate for the curvature of the cylindrical surface.

13. The spectacle lens according to claims 10 to 12, wherein: The second lens portion comprises a cylindrical surface, the cylindrical surface of the second lens portion being arranged to cooperate with the cylindrical surface of the first lens portion to provide the cylindrical interface.

14. The spectacle lens of claims 10 to 13, comprising a major axis and a minor axis, the cylindrical interface having a curved profile across the major axis.

15. The eyeglass lens of claim 14, wherein the cylindrical interface has a straight profile across the minor axis.

16. The eyeglass lens according to claims 10 to 15, wherein the holographic optical element is configured to act as a plane mirror or a plane transmission hologram.

17. The spectacle lens according to claims 10 to 16, wherein the spectacle lens is configured such that the total optical power of the holographic optical element is determined by the sum of the optical power of the hologram of the holographic optical element and the optical power resulting from the curvature of the cylindrical interface.

18. The spectacle lens according to any one of the preceding claims, wherein the spectacle lens has a spherical or spherocylindrical outer contour.

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