WO2025195797A1

WO2025195797A1 - Method for manufacturing a blank, method for manufacturing an optical system, optical system

Info

Publication number: WO2025195797A1
Application number: PCT/EP2025/056200
Authority: WO
Inventors: Gregorius Petrus Franciscus BISKOP; Julius HOFMAN; Catherine Cornelia Johanna HAGE
Original assignee: Addoptics BV
Current assignee: Addoptics BV
Priority date: 2024-03-22
Filing date: 2025-03-06
Publication date: 2025-09-25
Anticipated expiration: 2026-09-22

Abstract

The present invention relates to a method for manufacturing a blank (1) for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses. The present invention also relates to a method for manufacturing an optical system (10) for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses Furthermore, the present invention relates to an optical system (10) for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, comprising a blank (1), a functional element and a further blank (1').

Description

DESCRIPTION

Title

Method for manufacturing a blank, method for manufacturing an optical system, Optical system

Background

The present invention relates to a method for manufacturing a blank for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses. The invention further relates to a method for manufacturing an optical system for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses. Furthermore, the invention relates to an optical system.

There is a variety of technologies for manufacturing optical elements that can be used for an augmented and/or virtual reality application. Firstly, optical elements can be produced by mechanical processing, especially by sawing, cutting, grinding and/or a combination thereof. So-called optical blanks, or briefly just blanks, can serve as initial or base material for processing. Generally speaking, mechanical processing can - depending on the desired application - go along with an unsatisfactory surface roughness due to surficial unevenness. An uneven surface on the other hand can result in an insufficient optical performance of the optical element. For instance, an uneven surface may result in an undesired and therefore detrimental scattering of light.

A second manufacturing technology of optical elements is the process of casting. Casting can be used as an alternative or additional technology to mechanical processing. For that purpose, a raw material from which the optical element is to be produced can be molten and cast into a mould that comprises a mould cavity. However, conventionally, casting necessitates heavy metallic moulds whose production is cost-intensive. Furthermore, a metallic mould can only be used for a specific geometry of a specific optical element. Such a mould of course could be further milled or processed otherwise in order to change the mould cavity so as to manufacture optical elements with another geometry. However, such an approach with an additional processing of the mould involves additional investment of resources and is therefore deemed suboptimal. Optical elements can also be cast using two- component substances into glass moulds.

Thirdly, optical elements can be printed by means of a three-dimensional printing technology (3D printing). Three-dimensional printing is the technology of droplet deposition in controlled amounts at pre-determined locations on a substrate by means of a dispensing unit, particularly based on an inkjet technology. Movement of the dispensing unit may be controlled, based on pre-received data. After deposition, the droplets are allowed to settle and are given sufficient time to solidify. The process of solidification may be supported by, for instance, UV-radiation and/or forced loss of thermal energy. Depositing droplets layer by layer brings about an end product. One possible drawback of 3D printing is the so-called staircasing which refers to uneven surfaces at the verges of the end product which resemble staircases due to the layer-by-layer deposition of material. Another possible problem within the framework of 3D printing is the proclivity of materials to yellowing and hazing.

Aforementioned and other technologies can be combined for the manufacturing of optical elements, especially to avoid their respective downsides and therefore to bring about optimal optical elements and systems.

Typically, cylindrical blanks are used for the production of optical elements and systems. Such blanks comprise at a first end a circular base area and at a second end formed at an opposite direction of the circular base area a convex surface with a predefined curve. Such traditional blanks are not favorable for the manufacturing optical elements that are used in augmented reality (AR) and/or virtual reality (VR) applications since blanks for AR and/or VR applications necessitate - compared with conventional ophthalmic glasses - firstly blanks with larger diameters and secondly involve a higher degree of mechanical processing and waste. Due to the aforementioned drawbacks, manufacturing of AR and/or VR applications, particularly of AR and/or VR headsets/glasses, can be costly.

Disclosure of the invention

It is an object of the present invention to provide an optimized blank for AR and/or VR applications.

The object of the present invention is achieved by method for manufacturing a blank for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, wherein a mould with a mould cavity is provided, wherein the mould cavity comprises a first cavity and a second cavity that at least partially surrounds the first cavity, wherein a cast substance is cast into the mould cavity throughout the first cavity and the second cavity, wherein the cast substance forms the blank, wherein the blank comprises an optical section arising from the cast substance in the first cavity and a mounting section arising from the cast substance in the second cavity, wherein the mounting section at least partially surrounds the optical section, wherein the blank is separated from the mould.

By providing a blank that is manufactured according to the invention, much less blank material or (cast) substance can be used. Therefore, material costs for the manufacturing of AR- and/or VR-specific blanks can be reduced. Also, the necessity of mechanically processing the blanks can be reduced to a minimum since AR- and/or VR-specific blanks are not cylindrical but rather comprise a geometry that resemble already to the AR- and/or VR- specific geometry in the final product. Minor mechanical processing with little waste therefore can yield the final product. In other words, regardless of material costs, manufacturing costs can be reduced too by means of the inventive method. Moreover, the manufacturing of such AR- and/or VR-specific blanks can be carried out easily, at most with minor changes, with or within existing traditional ophthalmic production lines.

For the production of a blank for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, a mould is initially provided. The mould can be a one- piece or a multi-piece mould. A preferred material for the mould is an elastomer, such as silicon rubber. Such materials may not provide sufficient rigidity to make the mould suitable for casting with a desired tolerance. That’s why the mould can comprise a rigid, for instance metallic, skeleton as an insert. Preferably, the skeleton has a fluid-permeable, for instance armor- or cage-like structure. The skeleton can comprise an organic polymer, like Polyethylene terephthalate glycol (PTEG), polyethylene or a combination of two. In another implementation, the skeleton can comprise one or more metals, such as iron, chromium, vanadium, magnesium, copper or a combination of the aforementioned. The skeleton can be formed as an inner skeleton, as an insert for the mould, or as an exoskeleton that can be provided at least partially outside of the mould.

Preferably, the mould can be made of a translucent, high tear strength, styrene and Pll resistant, low shrinkage and two-component silicone rubber whose hardness can be changed.

The mould comprises a mould cavity, wherein the mould cavity comprises a first cavity and a second cavity that at least partially surrounds the first cavity. The first cavity and the second cavity are sections of or within the one single mould cavity. The mould can comprise side walls, wherein each side wall can be flat, convex or concave. It is also conceivable that one or many side walls comprise respectively differently shaped segments. In other words, for instance, a side wall can comprise a flat segment and additionally a concave segment. Alternatively, a side wall can comprise a flat segment and additionally a convex segment. Alternatively, a side wall can comprise multiple flat segments. A cast substance is cast into the mould cavity throughout the first cavity and the second cavity, wherein the cast substance forms the blank. The cast substance can be a resin, particularly a two-component resin. Furthermore, the blank comprises an optical section arising from the cast substance in the first cavity and a mounting section arising from the cast substance in the second cavity, wherein the mounting section at least partially surrounds the optical section. In a last step of the method, the blank is separated from the mould.

According to a preferred embodiment of the invention, the optical section comprises a curved surface and the mounting section comprises a flat surface. The optical section comprises two opposing surfaces. Preferably, the optical section comprises a convex and a concave surface. The optical section can also comprise a flat surface that can be mechanically processed, particularly milled, in order to generate a convex or concave surface.

Furthermore, the mounting section preferably has two flat surfaces. A thickness of the mounting section, preferably along a viewing direction of the optical section, can be greater, equal or smaller than a thickness of the optical section. All surfaces, particularly a surface of the optical section, can be surfaced, polished, finished or otherwise processed.

In a preferred embodiment of the invention, the optical section comprises an eye-side surface and a world-side surface, wherein the world-side surface is substantially convex. A convex geometry of the world-side surface can enhance reflection features of the optical section, thereby increasing the quality and performance of an optical element. Preferably, the eye-side surface of the optical section is concave, the convex world-side surface and the concave eye-side surface being substantially parallel.

In an advantageous embodiment of the invention, the mounting section comprises a, particularly stepped, flange. The flange can be formed perpendicularly to a main extension area or a surface of the mounting section. The flange can comprise one or multiple recesses and/or one or multiple protrusions, particularly for connection purposes with the blank and/or the functional element. Furthermore, the flange can be curved or angled and therefore comprise one or multiple segments. Also, the flange can be stepped. Preferably, the flange extends, at least substantially, parallel to a viewing direction of the blank or optical section. Also, the flange can comprise one or multiple perforations, holes or the like, for instance for de-airing and/or material saving and/or weight reduction purposes.

Preferably, the flange is formed at an edge of the mounting section () and is particularly formed as a closed curve. The flange can protect a functional element that can be mounted in or on the blank from external effects. The flange can also be used as a clamping means for the functional element. Alternatively or additionally, the flange can be used as a connecting means, especially a clamping means, with another blank. It is conceivable that the shape of the curve comprises one or two sections that are semi-circles. The curve can also be rectangular or at least comprise a linear section, for instance for aesthetic and/or artistic purposes. However, it is also conceivable that the curve is not closed but rather extends along a specific and predetermined length on or at the mounting section. The nonclosed flange can also comprise gaps or disruptions. A thickness of the flange can be constant along its entire edge length.

According to an advantageous embodiment of the invention, the flange comprises two linear sections that are arranged parallel to each other. Preferably, the linear sections are formed at an upper and a lower end of an AR- and/or VR-glasses that will be produced by means of a blank manufactured by an inventive method. Between the linear sections can be formed respectively a semi-circle section.

In an advantageous embodiment of the invention, the mounting section is at least partially mechanically processed, particularly milled, to form a mounting structure, particularly a flange or a stepped flange. The integration of a functional element at or within a blank can necessitate a variety of mounting structures, a flange being only an option. Milling or edging or other processing technologies can be used to create the mounting structure that is formed as a monobloc with the mounting section. A stepped flange has the advantage that the flange comprises more than one diameter, especially inner diameter.

Preferably, the mounting section comprises a first surface and a second surface that is arranged parallel to the first surface, wherein the first surface and the second surface are spaced apart, particularly along a viewing direction. The first surface and the second surface can be formed at a world-side or an eye-side of the blank. Both surfaces are preferably flat surfaces. The second surface can be a supporting surface for supporting, leveling and positioning a functional element. The functional element can be connected to the second surface by adhesion, for instance by means of an optical bonding agent, or by clamping force or both. By connecting the functional element with the second surface an air gap can be formed between the first surface and the functional element. The functional element can comprise nanogratings that - in an optical element or optical system, especially an AR- and/or VR-glasses, manufactured by the blank - receive light from a projector (typically near the temples or eyebrows) a nd guide it to a user’s eye. Aforementioned air gap is required in order to protect the nanogratings and therefore the functionality of the optical element or system. Parallelism between the first surface and the second surface can ensure that there is no physical contact between the functional element and the first surface. The first surface and the second surface can be particularly formed perpendicularly to the abovementioned flange. A connecting surface that can be formed parallel to the flange can connect the first surface to the second surface. The combination of the first surface, the connecting surface and the second surface can be called a step. Furthermore, a length of the connecting surface along the viewing direction or parallel to the flange correlates with a volume of the air gap formed between the first surface and the functional element. The viewing direction can be parallel to the flange or a main extension direction of the flange.

In a preferred embodiment of the invention, the mounting section comprises a third surface that is arranged parallel to the second surface, wherein the second surface and the third surface are respectively spaced apart, particularly along a viewing direction. The third surface can be an end face of the flange. Preferably, the first surface, the second surface and the third surface are parallel to each other. A further connecting surface that is formed perpendicular to the second surface and the third surface can connect the second surface to the third surface. The combination of the second surface, the further connecting surface and the third surface can be called a further step.

In an advantageous embodiment of the invention, the optical section comprises a circular cross section.

According to an advantageous embodiment of the invention, the optical section comprises an eye-side surface and a world-side surface, wherein material of the optical section is removed. The removal of material can be carried out to set a specific diopter to the optical section. The eye-side surface and the world-side surface can respectively be concave or convex. The amount of material removed determines a thickness of the optical section. The thickness is further determined by the convexity or concavity.

In a further preferred embodiment of the invention, the removal of material is performed from the world-side surface towards the eye-side surface. The world-side surface is preferably convex while the eye-side surface is preferably concave. Consequently, processing the world-side surface to a specific diopter is easier - hence less costly - than processing the eye-side surface. However, it is conceivable that the removal of material is performed in both directions along the viewing direction, from the world-side surface towards the eye-side surface and from the eye-side surface towards the world-side surface. The removal of material can also be performed from the eye-side surface towards the world-side surface. A major feature of the invention is that all recessed surfaces are finished. In other words, such recessed surfaces do not need to be post-processed after the blank is manufactured which is advantageous since surfacing and polishing equipment cannot optimally reach into recessed areas for finishing a surface. All protruding surfaces are semi-finished. In other words, they comprise a curve but still need to be post-processed in order to comprise optimal optical properties. This means the protruding surface can undergo surfacing & polishing in order to shape the required dioptry in the lens. As the surface is protruding, the equipment can easily work this surface without risk of running into other parts of the lens. According to a particularly preferred embodiment, prior to casting the cast substance into the mould cavity, a functional element is placed into the mould cavity, wherein the blank comprises the optical section, the mounting section and the functional element. In such an embodiment the functional element can be fully or at least partially embedded into the blank. An advantage that comes along with the functional element - especially a waveguide - being embedded into the blank is that a separate connecting step, wherein the functional element will be connected to the blank by means of adhesion or clamping, becomes dispensable.

Preferably, prior to placing the functional element into the mould cavity, a holder for supporting, positioning and aligning the functional element is placed into the mould cavity, or the functional element is connected to the holder to form a holding unit, wherein the holding unit is placed into the mould cavity.

A holder is an element that keeps the functional element in a desired position within the blank to be manufactured. In other words, the holder prevents the functional element from translational as well as rotational movement. Thus, the holder also accomplishes alignment of the functional element. Motion prevention within the meaning of the invention refers to both motion prevention during the manufacturing process as well as later in operation/use of the blank. Due to the fixed position and proper alignment of the functional element in a predetermined and desired location within the blank, quality and performance of the optical element or system that will be produced starting from the blank can be increased due to an optimized orientation of the functional element relative to the eye of a user of the optical element or system. Furthermore, a holder increases the mechanical stability of the functional element, especially during the manufacturing process, thereby not only preventing the functional element from an unwanted linear displacement and rotation but also from breaking or otherwise suffering mechanical damage. The holder can be connected directly or indirectly to the functional element. Furthermore, the holder can be symmetric or asymmetric. Moreover, the holder can be connected to the functional element positively, that is by means of a form-fit. Alternatively, the holder can be connected or bonded to the functional element firmly. The holder can comprise one or protrusions. The protrusions can be formed equidistantly to each other, for instance along a circumferential direction of the holder. The holder can be a planar/2D element with a recess in a middle section of the holder, the recess having a complementary shape to the contour of the functional element which results in the functional element fitting into the recess. Therefore, for instance, the recess can be rectangular. Furthermore, the holder can comprise a planar section serving as a substrate and an insertion section for inserting or placing the functional element into or onto it, the insertion section being firstly formed perpendicular to the planar section and secondly having a - in a top view - rectangular shape which results in the functional element being placeable or insertable into the insertion section. In other words, the insertion section can comprise lateral walls/protrusions defining a precise position for the functional element. Furthermore, the holder can comprise one or many convex sections and/or one or many concave sections in order to optimally fit into a mould. In addition or alternatively, the functional element and the holder can be arranged, at least substantially, coplanar with each other or, alternatively, parallel to each other while being spaced apart from each other. Preferably, the holder is manufactured by means of a three-dimensional printing technology, moulding and casting: Firstly, a master of the holder can be printed, particularly using a UV-cured ink. Then, a mould can be manufactured, especially a mould made of silicon rubber. Finally, the holder can be cast into the silicon mould, wherein the cast substance can be a resin, particularly a two-component resin. Preferably, the holder and a main body of the blank are manufactured by the same (cast) substance, the main body and the holder particularly having the same refractive index. Using the same substance for the manufacturing of the holder and the main body of the blank is advantageous as there will be no phase boundaries between the holder and the main body at which light could be disadvantageously reflected or scattered. The holder will be, so to say, invisible. In other words, a technical effect of such an embodiment with a holder is that the functional element will appear to be freely suspended in the blank and in the later optical element or system. This quasi-monolithic embodiment increases the optical performance. In areas where the holder is arranged, a high degree of clarity will be accomplished. Furthermore, using the same (cast) substance for the holder and the main body is advantageous as - in case of temperature changes - both the holder and the main body will expand to the same extent, which will not create unnecessary tensions within the blank which might otherwise result in mechanical damage, such as cracks or ruptures within the blank. Preferably, the cast substance used for the manufacturing of the holder and the main body is a transparent substance, for instance a transparent resin. Suitable substances are also polymethylmethacrylate, polycarbonate, silicones, urethane, high refractive index materials or a combination thereof.

According to another embodiment of the invention, the optical section (3) comprises an eyeside surface and a world-side surface, wherein the world-side surface is finished or semifinished.

According to another embodiment of the invention, the optical section (3) comprises an eyeside surface and a world-side surface, wherein the eye-side surface is finished or semifinished.

According to another embodiment of the invention, the optical section comprises a, particularly spherical, curvature or shape or surface. Another subject of the invention is a method for manufacturing an optical system for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, wherein a blank, preferably manufactured according to any of abovementioned embodiments, is provided, wherein a functional element is mounted on the mounting section, wherein a further blank, preferably manufactured according to any of abovementioned embodiments, is provided and mounted on the functional element and/or on the blank, wherein the blank, the functional element and the further blank form the optical system. An optical system is an assembly that comprises two blanks and a functional element, especially a waveguide, wherein the functional element is arranged between the two blanks. The two blanks can be connected to each other such that an end face of the flange of the blank is flush with an eye-side surface of the mounting section of the further blank. Preferably, the blank has a larger projected surface than the further blank. In other words, the further blank is smaller than the blank and therefore fits into the blank, wherein the flange of the blank surrounds the flange of the further blank. Preferably, the flange of the blank has a higher length than the flange of the further blank. The respective optical sections of the blank and the further blank can be substantially identical. In other words, the optical section of the blank can comprise, for instance, the same thickness, the same convex worldside surface, the same concave eye-side surface and the same diopter than the optical section of the further blank. A blank within the meaning of the invention can refer to a postprocessed blank too. A post-processed blank can also be named a coverlens since it covers and mechanically protects the functional element.

According to an advantageous embodiment of the invention, the functional element is clamped between the blank and the further blank, wherein the further blank is connected to the blank, particularly by means of an adhesive. Preferably, an outer dimension of the flange of the further blank is greater than an inner dimension of the flange of the blank in order to ensure clamping forces. Clamping forces can act between an inner flange surface of the blank and an outer flange surface of the further blank. In other words, the blank can be named an outer blank, whereas the further blank can be designated an inner blank. Also, in order to ensure (sufficient) clamping forces or increase clamping forces, the flange of the blank can comprise one or multiple inwardly directed protrusions. Such protrusions can be formed perpendicularly to the flange. Said protrusions can decrease the effective inner diameter of the flange and therefore ensure or increase the clamping forces. Alternatively or additionally, in order to ensure (sufficient) clamping forces, or increase clamping forces, the flange of the further (inner) blank can comprise one or multiple outwardly directed protrusions. Such protrusions can be formed perpendicularly to the flange of the further blank. Clamping can be carried out automatically or manually.

In an advantageous embodiment of the invention, the functional element is mounted such that an air gap is formed between the functional element and the blank and a further air gap is formed between the functional element and the further blank. Preferably, the air gap and the further air gap are formed such that a minimum distance between the functional element and the respective blank or further blank - at least in a middle section of the functional element - amounts to at least 0,03 mm, preferably more than 0,07 mm, more preferably more than 1 mm in order to protect the nanogratings and therefore the functionality of the optical element. However, in an edge section or boundary section of the functional element, there is no air gap neither a further air gap due to the physical connection of the functional element to the blank.

Another subject of the invention is an optical system for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, comprising a blank, a functional element and a further blank, wherein the blank comprises an optical section and a mounting section that at least partially surrounds the optical section, wherein the functional element is mounted on the mounting section, wherein the further blank is mounted on the functional element and/or on the blank, wherein the further blank comprises a further optical section and a further mounting section that at least partially surrounds the further optical section.

According to a preferred embodiment of the invention, the mounting section comprises a first surface and a second surface that is arranged parallel to the first surface, wherein the first surface and the second surface are spaced apart, particularly along a viewing direction. The first surface and the second surface can be formed at a world-side or an eye-side of the blank. Both surfaces are preferably flat surfaces. The second surface can be a supporting surface for supporting, leveling and positioning a functional element. The functional element can be connected to the second surface by adhesion, for instance by means of an optical bonding agent, or by clamping force or both. By connecting the functional element with the second surface an air gap can be formed between the first surface and the functional element. The functional element can comprise nanogratings that - in an optical element or optical system, especially an AR- and/or VR-glasses, manufactured by the blank - receive light from a projector (typically near the temples or eyebrows) a nd guide it to a user’s eye. Aforementioned air gap is required in order to protect the nanogratings and therefore the functionality of the optical element or system. Parallelism between the first surface and the second surface can ensure that there is no physical contact between the functional element and the first surface. The first surface and the second surface can be particularly formed perpendicularly to a flange. A connecting surface that can be formed parallel to the flange can connect the first surface to the second surface. The combination of the first surface, the connecting surface and the second surface can be called a step. Furthermore, a length of the connecting surface along the viewing direction or parallel to the flange correlates with a volume of the air gap formed between the first surface and the functional element. The viewing direction can be parallel to the flange or a main extension direction of the flange.

In an advantageous embodiment of the invention, an air gap is formed between the functional element and the blank and a further air gap is formed between the functional element and the further blank. Preferably, the air gap and the further air gap are formed such that a minimum distance between the functional element and the respective blank or further blank - at least in a middle section of the functional element - amounts to at least 0,03 mm, preferably more than 0,07 mm, more preferably more than 1 mm in order to protect the nanogratings and therefore the functionality of the optical element. However, in an edge section or boundary section of the functional element, there is no air gap neither a further air gap due to the physical connection of the functional element to the blank.

According to an advantageous embodiment of the invention, the blank comprises a flange and the further blank comprises a further flange, wherein the flange surrounds the further flange. Preferably, the flange has a higher length than the further flange in order for the flange to fully surround the further flange. The assembly comprising the blank and the further blank can be formed such that an end face of the flange is flush with an eye-side surface of the mounting section of the further blank.

Preferably, an end face of the functional element abuts against the flange or the further flange. The functional element preferably is a substantially two-dimensional element comprising a main extension direction. An end face of the functional element formed perpendicular to the main extension direction can be in physical contact with an inner side or surface of the flange or the further flange, for instance due to clamping of the functional element inside the blank or further blank. The inner surface particularly can improve the positioning of the functional element. Preferably, while the end face is in physical contact with an inner surface of the flange or further flange the functional element also is supported and positioned on a second surface of the blank or further blank, the second surface being formed perpendicularly to the inner surface. The inner surface can have an annular shape and further comprise multiple sections, for instance two linear and two semi-circle sections.

According to a preferred embodiment of the invention, an area of the functional element is larger than an area of the optical section. In other words, the functional element comprises a first area and a surplus area, the first area being equally as great as the area of the optical section. The surplus area comprises nanogratings that catch light from a projector (typically near the temples or eyebrows of a user of the optical system) and guide the light to the user's eye. The airgap is required in order to protect the nanogratings, and the supporting area near the edges is the only area where the waveguide can be touched without causing mechanical damage to the optical system.

In a preferred embodiment of the invention, the optical section and/or the further optical section comprise a circular cross section.

Preferably, the optical section and the further optical section comprise respectively an eyeside surface and a world-side surface, wherein both world-side surfaces are convex and both eye-side surfaces are concave.

According to an advantageous embodiment of the invention, the further flange is stepped.

According to a further embodiment of the invention, the flange is formed at an edge of the mounting section and the further flange is formed at a further edge of the further mounting section. Preferably, the edge and the further edge are formed as closed curves. The flange and/or the further flange can serve as connecting means as well as protecting means to protect the functional element from external effects. The flange and/or the further flange can also be used as clamping means for the functional element. The one or both curves can also be rectangular or at least comprise a linear section, for instance for aesthetic and/or artistic purposes. However, it is also conceivable that the curves are not closed but rather extend along a specific and predetermined length along the respective edge of the mounting section and/or further mounting section. Non-closed flanges can also comprise gaps or disruptions. A thickness of the flange can be constant along its entire edge length.

Features, technical effects, advantages and other characteristics of the inventive method for manufacturing a blank for an augmented reality and/or virtual reality application, of the inventive method for manufacturing an optical system and of the optical system can be combined.

Aforementioned and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of examples, the principles of the invention. The description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

Brief description of the drawings Figure 1 illustrates a traditional blank for manufacturing an optical element in a perspective view.

Figure 2a illustrates schematically in a cutaway view a first and a second embodiment of a blank manufactured according to an inventive method.

Figure 2b illustrates schematically the first and the second embodiment of

Figure 2a after a first mechanical processing step.

Figure 2c illustrates schematically the first and the second embodiment of

Figure 2a after a second mechanical processing step.

Figure 2d illustrates schematically the first and the second embodiment of

Figure 2a after a third mechanical processing step.

Figure 3 illustrates schematically in a top view two different embodiments of a blank manufactured according to an inventive method.

Figure 4 illustrates schematically an embodiment of a mould with a mould cavity according to the inventive method.

Figure 5 illustrates schematically a first embodiment of an inventive optical system in a cutaway view.

Detailed description

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

Where an indefinite or definite article is used when referring to a singular noun, e.g. “a”, “an”, “the”, this includes a plural of that noun unless something else is specifically stated.

Furthermore, the terms first, second, third and the like in the description and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described and/or illustrated herein. Figure 1 illustrates a traditional cylindrical blank 8 for manufacturing an optical element in a perspective view. Such traditional blanks comprise at a first lower end a circular base area, a cylindrical lateral surface and at a second upper end a convex surface with a predefined curve. Such traditional blanks are not favorable for the manufacturing optical elements that are used in augmented reality (AR) and/or virtual reality (VR) applications since blanks for AR and/or VR applications necessitate - compared with conventional ophthalmic glasses - firstly blanks with larger diameters and secondly involve a higher degree of mechanical processing and waste in order to design an AR- and/or VR-specific geometry. The AR- and/or VR-specific geometry is required to mount a functional element that serves as a display technology. Traditional blanks 8 can also be biconcave or biconvex and the like.

Figure 2a illustrates schematically in a cutaway view a first and a second embodiment of a blank 1 manufactured according to an inventive method. The first embodiment is illustrated on the left-hand side of Figure 2a, while the second embodiment is shown on the right-hand side of Figure 2a. Both embodiments were manufactured by means of the inventive method.

According to the inventive method, a mould with a mould cavity is provided, wherein the mould cavity comprises a first cavity and a second cavity that at least partially surrounds the first cavity. Further details with respect to the first cavity and the second cavity will be illustrated and described below in figure 4. In order to manufacture the blank 1, a liquid, fluidic or viscous cast substance will be cast into the mould cavity throughout the first cavity and the second cavity, wherein the cured cast substance forms the blank 1. The first cavity and the second cavity within the meaning of the invention and as shown in the figures are not necessarily to be understood as two discrete and separate cavities but rather as two sections or segments of one single and coherent cavity that is identical with the mould cavity. In other words, the first and second cavity are formed as one single voluminous continuum, the first cavity being fluidically connected to the second cavity.

The blank 1 comprises an optical section 3 arising from the cast substance in the first cavity and a mounting section 5 arising from the cast substance in the second cavity, wherein the mounting section 5 at least partially surrounds the optical section 3. In a final step of the inventive method, the blank 1 is separated from the mould. The separation can be done automatically or manually, also directly or by means of a further tool. Moreover, the separation can be simplified if the mould is made of a flexible material, for instance of silicon rubber.

Blanks as shown in figure 2a can be manufactured and used for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses or AR- and/or VR-headset. However, they need further processing in order to comprise an AR- and/or VR-specific geometry that allows mounting of a functional element, particularly of a waveguide, that serves as a display technology. Both embodiments in figure 2a do not comprise such AR- and/or VR-specific geometries and therefore are to be understood as a source body or original body for the production of an AR and/or VR-specific blank. Apart from one single surface respectively - one concave surface on the left-hand side and one convex surface on the right-hand side - both embodiments rather comprise only flat surfaces, and they particularly do not comprise any connecting means or clamping structures and/or the like for the mounting of a functional element on the blank 1. However, such connecting means and/or clamping structures and/or the like are not the only modifications that need to be implemented in order to create a blank 1 that meets requirements for the eligibility for use in an optical element and/or optical system. For instance, in order to obtain a desired diopter of the optical section 3, it can also be necessary to remove material form the optical section 3 which among others depends on the shape of the blank 1 right after the casting of the cast substance. As a result, users with different ophthalmic needs, that is with different glasses comprising different diopters, can be addressed or served with the final product, which is an optical element or an optical system. Eventually, a thickness and shape of the optical section 3 needs to be changed which will be further elucidated in the descriptions of the following figures.

It is also conceivable that the mould and the mould cavity are formed such that the degree to which mechanical processing is necessary is reduced to a minimum. In other words, the blank 1 can already comprise AR- and/or VR-specific geometries directly after the casting process. As a result, further mechanical processing becomes dispensable or can be at least reduced to a minimum which can reduce manufacturing time and costs.

Figure 2b illustrates schematically the first and the second embodiment of Figure 2a after a first mechanical processing step. Both embodiments are mechanically processed, especially milled and/or lathed, and material is removed respectively starting from a world-side surface W towards an eye-side-surface E. The respective eye-side surface E remains unchanged, while the world-side surface W of the first embodiment becomes convex, the world-side surface W of the second embodiment becomes concave. In either case, the respective world-side surface W and eye-side surface E are parallel to each other. Also, the respective eye-side-surface E can be finished in order to increase the optical performance of the blank 1 and the final product that will be produced from the blank 1. As a consequence, the respective thicknesses of the two embodiments is reduced and a specific diopter is respectively set. The mounting sections 5 remain unchanged too after the first mechanical processing step. In other words, during the first mechanical processing step, only the worldside surface W is being processed. The embodiments illustrated in figure 2b can also be manufactured by an alternative mould design or mould cavity. In other words, the embodiments as shown in figure 2b are manufactured without post-processing, particularly milling, of the blank 1.

Figure 2c illustrates schematically the first and the second embodiment of Figure 2a after a second mechanical processing step. It is to be noted that the first and the second mechanical processing step can be carried out simultaneously. After the second mechanical processing step, the mounting sections 5 of the first and second embodiment are formed such that a respective first surface 5.1 and a second surface 5.2 are created. The first surface 5.1 and the second surface 5.2 are formed parallel to each other. Both surfaces 5.1, 5.2 are rather small surfaces compared with a projected surface of the blank 1 as a whole, the projected surface being formed perpendicular to a viewing direction V. The viewing direction is to be understood as the position of a user’s eye Furthermore, the first surface 5.1 and the second surface 5.2 are spaced apart from each other along the viewing direction V. The second surfaces 5.2 are formed in the proximity of an edge of the mounting section 5. Moreover, a respective flange 5.3 is generated by mechanically processing the blank 1. The flanges 5.3 extend substantially parallel to the viewing direction V. Also, the flanges 5.3 are formed at the outmost edge of the mounting section 5 and extend from the world-side surface W towards the eye-side surface E. A connecting surface that is formed substantially perpendicular to the first surface 5.1 and the second surface 5.2 connects to first surface 5.1 to the second surface 5.2. A length or height of the connecting surface parallel to the viewing direction V determines the distance or gap between the first surface 5.1 and the second surface 5.2. The convex world-side surface W of the first embodiment on the left-hand side of figure 2c has a longer curve than the concave eye-side surface E of the first embodiment. The same applies to the second embodiment on the right-hand side of figure 2c: the concave world-side surface W has a longer curve than the eye-side surface E. The embodiments illustrated in figure 2c can also be manufactured by an alternative mould design or mould cavity. In other words, the embodiments as shown in figure 2c are manufactured without post-processing, particularly milling, of the blank 1.

With respect to a plane perpendicular to the viewing direction V, especially the abovementioned projected surface, the flanges 5.3 are formed as a closed curve around the optical section 3. Due to the flanges 5.3, a protective structure is generated for a functional element that can be mounted on the second surface 5.2. In that case, the flanges 5.3 act as a protective wall. It is also conceivable that the flanges 5.3 comprise gaps along their respective length along the respective edge. In such a case, the multiple sections of a flange 5.3 act as protective wallsA functional element can be mounted on the blank 1 , for instance, by connecting it to the second surface 5.2 by way of adhesion. It is also conceivable that the functional element, especially a waveguide, is clamped into the blank 1 , which will be further described in the following. Figure 2d illustrates schematically the first and the second embodiment of Figure 2a after a third mechanical processing step. In the third mechanical processing step, the optical section 3 will be further reduced in thickness. The third mechanical processing step involves particularly polishing and/or finishing of the world-side surface W for an optimum optical performance of the blank 1. For the second embodiment, shown on the right-hand side in the figures 2a to 2d, two alternative results are illustrated, depending on the diopter to be set to the optical section 3. The two options shown on the right-hand side of figure 2d comprise different convexities on their respective world-side surfaces W. Therefore, the optical section 3 on the upper right side of figure 2d has another diopter than the optical section 3 on the lower right side of figure 2d. all embodiments illustrated in figure 2d comprise a circular optical section 3 with a radius R. Furthermore, the thickness of the optical section 3 in the embodiment shown on the upper right side of figure 2d is not constant with respect to a radial direction, but the thickness is nonetheless symmetric. The flanges 5.3 comprise respectively an inner flange surface 6. A functional element can be mounted by way of clamping and by means of the inner flange surface 6 in the blank 1. An end face of the functional element can abut against the inner flange surface 6. In other words the end face can be in physical contact with the inner flange surface 6. The functional element preferably is a substantially two-dimensional element, for instance a foil, comprising a main extension direction, particularly formed perpendicularly to the viewing direction V. An end face of the functional element formed perpendicular to the main extension direction or parallel to the viewing direction V can be in physical contact with the inner flange surface 6. Due to the clamping and adhesion, sufficient forces can act between the blank 1 and the functional element so as to maintain the functional element in a desired position. The inner flange surface 6 particularly improves the positioning of the functional element. While the end face is in physical contact with the inner flange surface 6, the functional element also is supported and positioned on the second surface 5.2 of the blank, the second surface 5.2 being formed perpendicularly to the inner flange surface 6. The inner flange surface 6 has an annular shape. Moreover, the inner flange surface 6 comprises multiple sections, as will be described in the following.

Figure 3 illustrates schematically in a top view two different embodiments of a blank 1 manufactured according to an inventive method. The embodiment on the left-hand side of figure 3 differs from the embodiment on the right-hand side in that the second surface 5.2 of the right embodiment and/or its area is greater than the second surface 5.2 of the left embodiment. The flange 5.3, the inner flange surface 6 as well as the second surface 5.2 comprise respectively two linear and two semi-circle sections. Therefore, the outer contour of the blank 1 resembles a outer contour of a soccer stadium or a soccer pitch with running tracks around the pitch. Furthermore, the optical sections 3 comprise respectively a circular cross section. The top view illustrated in figure 3 is shown from the eye-side towards the world-side of the blank 1. The flanges 5.3 are formed at the edge, that is at an outmost segment, of the mounting section 5.

Figure 4 illustrates schematically an embodiment of a mould 4 with a mould cavity 4.1 according to the inventive method. The mould cavity 4.1 has two cavities 4.T, 4.1” or cavity sections 4.T, 4.1”, the first being a first cavity 4.T and the second being a second cavity 4.1”. The second cavity 4.1” at least partially surrounds the first cavity 4.T. In other words, at least one, preferably all outmost dimensions of the second cavity 4.1” are greater than an outmost dimension of the first cavity 4.T. The first cavity 4.T as illustrated in the embodiment in figure 4 has a circular cross section with a radius R. The double of the radius R, meaning 2R, is smaller than a maximum dimension M of the second cavity 4.1”, the maximum dimension M being perpendicular to the viewing direction V.

The mould 4 shown in figure 4 is a two-piece mould 4. However, it is also conceivable that that mould 4 is a one-piece mould 4. It is even conceivable that the mould 4 comprises three or more pieces. After casting the cast substance, the optical section 3 materializes in the first cavity 4.T. Analogously, the mounting section 5 solidifies and materializes in the second cavity 4.1”. Furthermore, the mould 4 can have one or more supply lines for the cast substance, the supply lines being formed in a base body of the mould 4 and feeding into the mould cavity 4.1. A first supply line can be assigned to the first cavity 4.T and a second supply line can be assigned to the second cavity 4.1”, thereby optimizing flow characteristics of the cast substance during the casting procedure. For illustration purposes and for the sake of simplicity, supply lines are not shown in figure 4. Also, the mould 4 can comprise one or more skeletons, for instance made of a metal, in order to increase a stiffness of the mould 4.

The mould embodiment shown in figure 4 comprises a multitude of surfaces. All surfaces except for one are flat. The single surface that is curved can be, regardless of the curve shown in figure 4, convex or concave.

Figure 5 illustrates schematically a first embodiment of an inventive optical system 10 in a cutaway view. The optical system 10 comprises a blank 1 , a functional element 7 and a further blank T. The blank 1 and the further blank T can be manufactured according to the abovementioned inventive method. The blank 1 comprises an optical section 3 and a mounting section 5 that at least partially surrounds the optical section 3. Furthermore, the functional element 7 is mounted on the mounting section 5. For this purpose, the functional element 7 is clamped in the volume formed between the inner flange surface 6. At the same time, the functional element 7 is positioned on the second surface 5.2. As a result, the functional element 7 is fixated in and/or at the mounting section 5. In other words, forces act on the functional element 7 in two perpendicular directions: firstly parallel to a main extension direction/area, especially radially inwards, due to clamping and secondly parallel to the viewing direction V due to adhesion. Afterwards, the further blank T is connected to the unit comprising the blank 1 and the functional element 7, wherein the further blank T comprises a further optical section 3’ and a further mounting section 5’ that at least partially surrounds the further optical section 3’. Such an optical system 10 can be used for augmented reality and/or virtual reality applications. Ideally, two of such optical systems 10 are combined to form AR- and/or VR-glasses, each optical system 10 being arranged at an eye of a user when in operation or use.

The optical section 3 comprises an eye-side surface E and a world-side surface W. Analogously, the further optical section 3’ comprise a further eye-side surface E’ and a further world-side surface W’. Both world-side surfaces W, W are convex and both eye-side surfaces E, E’ are concave.

The functional element 7 is mounted on the mounting section 5 such that an air gap A is formed between the functional element 7 and the blank 1 and a further air gap A’ is formed between the functional element 7 and the further blank T. A size or volume of the air gap A is determined by a distance or height between the functional element 7 and the first surface 5.1. In other words, a connecting surface formed substantially perpendicularly between the first surface 5.1 and the second surface 5.2 defines the volume of the air gap A. The air gap A also encompasses the section between the convex world-side surface W of the blank 1. Analogously, a size or volume of the further air gap A’ is determined by a further distance or further height between the functional element 7 and a further first surface 5.T. In other words, a further connecting surface formed substantially perpendicularly between the further first surface 5.T and the further second surface 5.2’ defines the volume of the further air gap A’. The further air gap A’ also encompasses the section between the concave eye-side surface E’ of the further blank T.

An area of the functional element 7 is larger than an area of the optical section 3. In other words, the functional element 7 comprises a first area and a surplus area, the first area being equally great than the area of the optical section 3, and the surplus area substantially being formed in the vicinity of the first surface 5.1 and the further first surface 5.T. The functional element 7 comprises nanogratings that catch light from a projector (typically near the temples or eyebrows of a user of the optical system 10) and guide the light to the user's eye. The air gap A and/or the further air gap A’ are required in order to protect the nanogratings, and the supporting area near the edges is the only area where the functional element/waveguide can be touched without causing mechanical damage to the optical system 10. Therefore, the functional element 7 is clamped at the edges of the blank 1 and further blank T. However, in a middle section, the functional element 7 is freely suspended. The further flange 5.3’ surrounds the flange 5.3. Both flanges 5.3, 5.3’ are stepped. The blank 1 is connected to the further blank T such that a third surface 5.4 of the blank 1 is flush with an eye-side of the mounting section 5. Such flushness brings about a smooth surface which improves aesthetics and haptics and therefore optimizes the user experience.

List of reference signs

1 Blank

T Further blank

3 Optical section

3’ Further optical section

4 Mould

4.1 Mould cavity

4.T First cavity

4.1” Second cavity

5 Mounting section

5’ Further mounting section

5.1 First surface

5.T Further first surface

5.2 Second surface

5.2’ Further second surface

5.3 Flange

5.3’ Further flange

5.4 Third surface

6 Inner flange surface

7 Functional element

8 Traditional cylindrical blank

10 Optical system

A Air gap

A’ Further air gap

E Eye-side surface

E Further eye-side surface

M Maximum dimension of the second cavity

R Radius of the first cavity

V Viewing direction

W World-side surface

W’ Further world-side surface

Claims

PATENT CLAIMS

1. Method for manufacturing a blank (1) for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, wherein a mould (4) with a mould cavity (4.1) is provided, wherein the mould cavity (4.1) comprises a first cavity (4.T) and a second cavity (4.1”) that at least partially surrounds the first cavity, wherein a cast substance is cast into the mould cavity (4.1) throughout the first cavity (4.T) and the second cavity (4.1”), wherein the cast substance forms the blank (1), wherein the blank (1) comprises an optical section (3) arising from the cast substance in the first cavity (4.T) and a mounting section (5) arising from the cast substance in the second cavity (4.1”), wherein the mounting section (5) at least partially surrounds the optical section (3), wherein the blank (1) is separated from the mould (4).

2. Method according to claim 1, wherein the optical section (3) comprises a curved surface and the mounting section (5) comprises a flat surface.

3. Method according to claim 1 or 2, wherein the optical section (3) comprises an eyeside surface and a world-side surface, wherein the world-side surface is substantially convex.

4. Method according to any one of the preceding claims, wherein the mounting section (5) comprises a, particularly stepped, flange.

5. Method according to claim 4, wherein the flange is formed at an edge of the mounting section (5) and is particularly formed as a closed curve.

6. Method according to claim 4 or 5, wherein the flange comprises two linear sections that are arranged parallel to each other.

7. Method according to any one of the preceding claims, wherein the mounting section (5) is at least partially mechanically processed, particularly milled, to form a mounting structure, particularly a flange or a stepped flange.

8. Method according to any one of the preceding claims, wherein the mounting section (5) comprises a first surface and a second surface that is arranged parallel to the first surface, wherein the first surface and the second surface are spaced apart, particularly along a viewing direction.

9. Method according to claim 8, wherein the mounting section (5) comprises a third surface that is arranged parallel to the second surface, wherein the second surface and the third surface are respectively spaced apart, particularly along a viewing direction.

10. Method according to any one of the preceding claims, wherein the optical section (3) comprises a circular cross section.

11 . Method according to any one of the preceding claims, wherein the optical section (3) comprises an eye-side surface and a world-side surface, wherein material of the optical section (3) is removed.

12. Method according to claim 11 , wherein the removal of material is performed from the world-side surface towards the eye-side surface.

13. Method according to any one of the preceding claims, wherein, prior to casting the cast substance into the mould cavity, a functional element is placed into the mould cavity, wherein the blank (1) comprises the optical section (3), the mounting section (5) and the functional element.

14. Method according to claim 13, wherein, prior to placing the functional element into the mould cavity, a holder for supporting, positioning and aligning the functional element is placed into the mould cavity, or the functional element is connected to the holder to form a holding unit, wherein the holding unit is placed into the mould cavity.

15. Method according to any one of the preceding claims, wherein the optical section (3) comprises an eye-side surface and a world-side surface, wherein the world-side surface is finished or semi-finished.

16. Method according to any one of the preceding claims, wherein the optical section (3) comprises an eye-side surface and a world-side surface, wherein the eye-side surface is finished or semi-finished

17. Method according to any one of the preceding claims, wherein the optical section comprises a, particularly spherical, curvature or shape or surface.

18. Method for manufacturing an optical system (10) for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, wherein a blank (1), preferably manufactured according to any of the claims 1 to 14, is provided, wherein a functional element is mounted on the mounting section (3), wherein a further blank (T), preferably manufactured according to any of the claims 1 to 14, is provided and mounted on the functional element and/or on the blank (1), wherein the blank (1), the functional element and the further blank (1’) form the optical system (10).

19. Method according to claim 18, wherein the functional element is clamped between the blank (1) and the further blank (T), wherein the further blank (T) is connected to the blank (1), particularly by means of an adhesive.

20. Method according to claim 18 or 19, wherein the functional element is mounted such that an air gap is formed between the functional element and the blank (1) and a further air gap is formed between the functional element and the further blank (T).

21. Optical system (10) for an augmented reality and/or virtual reality application, particularly AR- and/or VR-glasses, comprising a blank (1), a functional element and a further blank (T), wherein the blank (1) comprises an optical section (3) and a mounting section (5) that at least partially surrounds the optical section (3), wherein the functional element is mounted on the mounting section (5), wherein the further blank (T) is connected to the functional element and/or the blank (1), wherein the further blank (T) comprises a further optical section (3’) and a further mounting section (5’) that at least partially surrounds the further optical section (3’).

22. Optical system (10) according to claim 21 , wherein the mounting section (5) comprises a first surface and a second surface that is arranged parallel to the first surface, wherein the first surface and the second surface are spaced apart, particularly along a viewing direction.

23. Optical system (10) according to claim 21 or 22, wherein an air gap is formed between the functional element and the blank (1) and a further air gap is formed between the functional element and the further blank (T).

24. Optical system (10) according to any of the claims 21 to 22, wherein the blank (1) comprises a flange and the further blank (1’) comprises a further flange, wherein the flange surrounds the further flange.

25. Optical system (10) according to any of the claims 21 to 24, wherein an end face of the functional element abuts against the flange or the further flange.

26. Optical system according to any of the claims 21 to 25, wherein an area of the functional element is larger than an area of the optical section (3).

27. Optical system (10) according to any one of the claims 21 to 26, wherein the optical section (3) and/or the further optical section (3’) comprise a circular cross section.

28. Optical system (10) according to any of the claims 21 to 27, wherein the optical section (3) and the further optical section (3’) comprise respectively an eye-side surface and a world-side surface, wherein both world-side surfaces are convex and both eye-side surfaces are concave.

29. Optical system (10) according to any one of the claims 24 to 28, wherein the further flange is stepped.

30. Optical system (10) according to claim 29, wherein the flange is formed at an edge of the mounting section (5) and the further flange is formed at a further edge of the further mounting section (5’).