Optical system and method for manufacturing an optical element

Abstract

The present invention relates to an optical system (1), particularly for an augmented reality and / or virtual reality application, with a first optical element (10), a second optical element (20) and a third optical element (30), wherein the first optical element (10) and the third optical element (30) are ophthalmic elements, wherein the second optical element (20) is arranged, at least partially, between the first optical element (10) and the third optical element (30), and wherein the second optical element (20) comprises a functional element (22), wherein the second optical element (20) comprises a holder (24) for supporting, positioning and aligning the functional element (22). The present invention also relates to a method for manufacturing an optical part (40). Furthermore, the present invention relates to such an optical part (40).

Description

[0001] DESCRIPTION

[0002] Title

[0003] Optical system and method for manufacturing an optical element

[0004] Background

[0005] The present invention relates to an optical system, particularly for an augmented reality and / or virtual reality (AR and / or VR) application. The invention further relates to a method for manufacturing such an optical system. An optical system refers to a system comprising multiple optical elements.

[0006] 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 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] Currently, tremendous efforts are being made to integrate display technologies into prescription glasses or combine display technologies with prescription glasses, thereby creating an optical system that comprises on the one hand a said display technology and on the other hand one or many traditional ophthalmic lenses, each with a specific diopter. A display technology comprises a light engine that generates light and an optical combiner (particularly a waveguide) that redirects the light into a user’s eye. Such an optical system is sometimes called a smartlens and is suitable to serve as an AR and / or VR implementation.

[0011] A current drawback of such optical systems is the optimal positioning and aligning of the display technology within the optical system.

[0012] Disclosure of the invention

[0013] It is an object of the present invention to provide an optical system that provides a solution to the aforementioned problem.

[0014] The object of the present invention is achieved by an optical system, particularly for an augmented reality and / or virtual reality application, with a first optical element, a second optical element and a third optical element, wherein the first optical element and the third optical element are ophthalmic elements, wherein the second optical element is arranged, at least partially, between the first optical element and the third optical element, and wherein the second optical element comprises a functional element, wherein the second optical element comprises a holder for supporting, positioning and aligning the functional element. A holder is an element that keeps the functional element in a desired position within the optical system, more precisely in a desired position within the second optical element. 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 during usage of the optical system after having finished its manufacturing. Due to the fixed position and proper alignment of the functional element in a predetermined and desired location within the optical system, quality and performance of the optical system can be increased due to an optimized orientation of the functional element relative to the eye of a user of the optical 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. Moreover, the optical system preferably is a combination of one or more prescription glasses with a display technology, the latter being especially an AR and / or VR technology. In other words, it is advantageously possible to turn the display technology on and off so that a user can use the optical system as conventional prescription glasses. Such an implementation enables a compact design, while offering simultaneously functionality and adequate form / aesthetics.

[0015] The optical system comprises a first optical element, a second optical element and a third optical element. Preferably, the three optical elements are arranged in a flush manner. In other words, the first optical element can comprise a first frame section, the second optical element can comprise a second frame section and the third optical element can comprise a third frame section, the first, second and third frame section having each a same geometry and all three frame sections being stacked in an overlapping manner. It is also conceivable that the three frame sections are arranged in a concentric manner, each frame section comprising a different geometry. The second optical element can be clamped within the first or third optical element. Preferably, the three frame sections can be connected to each other in an interlocking or form-fit manner, thereby rendering it possible to disassemble the optical system non-destructively. This way, single components of the optical system, for instance one of the three optical elements in case of mechanical damage, can be replaced easily and in an economic fashion. The concept of assembling or arranging the first, second and third optical element such that all three optical elements are connected to each other mechanically can be named an encapsulation concept since the second optical element can be encapsulated by and within the first and third optical element.

[0016] The first optical element and the third optical element are ophthalmic elements. In other words, the first optical element and the third optical element respectively comprise a specific geometry and therefore a specific diopter. The first optical element is, preferably, a lens facing the human eye. The third optical element is, preferably, a further lens facing away from the human eye or, put another way, facing an object or the environment. Preferably, the third element comprises a convex geometry for enhanced reflection features of the optical system, thereby increasing the quality and performance of the optical system. It is conceivable that the diopters of the first optical element and the third optical element cancel each other out, rendering the optical system also suitable for anyone who does not need prescription glasses. In other words, a total diopter of the optical system can be zero.

[0017] The second optical element is arranged, at least partially, between the first optical element and the third optical element. The second optical element further comprises the functional element. The functional element is, preferably and at least partially, embedded within the second optical element such that a material of the second optical element mechanically protects the functional element from external impacts. Due to the intermediate or middle position of the second optical element - between the first and third optical element - the mechanical stability and protection of the functional element is further increased. The functional element is or comprises preferably a display unit that preferably comprises a (reflective or diffractive) waveguide.

[0018] The optical system comprises, according to the invention, a holder for positioning, aligning and mechanically supporting the functional element. The functional element can comprise a, at least partially, rectangular contour. Functional elements can also be circular or comprise a circular section. Also, shapes / contours / sections other than rectangular or circular are conceivable. Also, a combination of a multitude of shapes / contours / sections is possible. 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.

[0019] 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, molding and casting: Firstly, a master of the holder can be printed, particularly using a UV-cured ink. Then, a mold can be manufactured, especially a mold made of silicon rubber. Finally, the holder can be cast into the silicon mold, wherein the cast substance can be a resin, particularly a two-component resin.

[0020] Preferably, the mold 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.

[0021] According to an advantageous embodiment of the invention, the holder and a main body of the second optical element are manufactured by the same 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 second optical element is advantageous as there are 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 is that the functional element will appear to be freely suspended in the second optical element. This quasi- monolithic embodiment increases the optical performance of the (overall) optical system. In areas where the holder is arranged, a high degree of clarity will be accomplished. Furthermore, using the same 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 tension within the second optical element which might otherwise result in mechanical damage, such as cracks or ruptures within the second optical element. Preferably, the 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.

[0022] In a preferred embodiment of the present invention, the holder is a one-piece or multiplepiece element. The functional element can be connected and / or bonded unilaterally to a one- piece holder, thereby creating a holding unit. The holding unit then can be placed into a mould cavity and the main body substance of the second optical element can be cast until the main body is solidified / cured which results in the holding unit being embedded / incorporated partially or entirely within the main body of the second optical element. Also, the functional element can be connected and / or bonded to a multiple-piece, especially two-piece, holder. As a result, the functional element can be held and (mechanically) protected, for instance, bilaterally, for instance during the casting of the main body substance. As a result, the pressure on the functional element during the manufacturing process of the second optical element can be decreased and possible damages prevented. In case of a multiple-piece holder the single pieces can be connected to each other via snapping, clamping, bonding etc.

[0023] According to a preferred embodiment of the invention, the functional element is connected to the holder by means of an optical bonding agent. The optical bonding agent can be a transparent material with the same refractive index as the holder substance. By means of an optical bonding agent reflection between two different phases, that is in the phase boundary, can be eliminated or at least reduced to a minimum. Moreover, usage of an optical agent prevents possible air gaps between the holder and the functional element or reduces them at least to a minimum. As a result of one single substance for the holder and the functional element as well as of the prevention of air gaps an optimized optical performance of the optical system can be achieved.

[0024] Preferably, the holder comprises at least one holding arm that is connected to the functional element. A holding arm can remove at least one degree of freedom. Increasing the number of holding arms can increase the stiffness of the functional element. Therefore, preferably, the functional element’s position is fixed by means of multiple holding arms. Moreover, the connection between the at least one holding arm and the functional element can be formed between a first end of the holding arm and an edge of the functional element (a quasi-point contact) or, alternatively, an area of the functional element formed at a frame section of the functional element can rest on a first end section of the holding arm (area contact). The at least one holding arm can be arranged perpendicularly to an edge of the functional element or an angle, preferably between 0° to 90°, can be formed between the holding arm and the functional element.

[0025] According to an advantageous embodiment of the invention, the functional element is or comprises, at least substantially, a two-dimensional element, particularly a functional foil or a polarizer. Preferably, the substantially two-dimensional functional element is arranged parallel to an outer surface of the second optical element. Preferably, the at least one holding arm is coplanar with the functional element. Alternatively - or in case of multiple holdings arms additionally - a main extension axis of at least one holding arm can be parallel to a main extension area of the functional element.

[0026] In an advantageous embodiment of the invention, the functional element comprises four edges, wherein at least one holding arm is connected to each of the four edges. Preferably, the functional element comprises a rectangular or quadratic contour. Each holding arm can be advantageously connected to one edge of the functional element, thereby creating a stiff functional element at a fixed position within the second optical element. Preferably, at least one pair of holding arms, each one of the two holding arms being connected to an opposing edge of the functional element, is arranged colinearly.

[0027] According to a preferred embodiment of the invention, the functional element comprises four corners, wherein at least one holding arm is connected to each of the four corners.

[0028] Preferably, the holding arms are arranged symmetrically. In order to increase the stiffness of the functional element, especially during the manufacturing process, holding arms can be connected to the edges and to the corners of the functional element.

[0029] Another subject of the present invention is a method for manufacturing an optical part, particularly for an augmented reality and / or virtual reality application, wherein in a first step a mould comprising a mould cavity is provided, in a second step a functional element and a holder are placed into the mould cavity, in a third step a substance is cast into the mould cavity, and in a fourth step the cast substance is cured such that it - after having cured - forms a main body of the optical part, wherein the optical part comprises the main body, the functional element and the holder.

[0030] Aforementioned features, advantages and technical effects of the inventive optical system and its embodiments set out above apply also to the inventive method.

[0031] For an easy removal of the optical part from the mould cavity, 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.

[0032] Furthermore, the mould can be designed such that it comprises one or many reception sections for receiving the holder. The reception sections can be formed geometrically in a variety of ways. For instance, the mould can comprise one or many protrusions while the holder comprises complementary (to the protrusions) recesses for connecting the holder to the mould. Alternatively, the mould can comprise recesses while the holder can comprise complementary protrusions. Such embodiments help position and align the holder and thus also the functional element.

[0033] The curing during the fourth step of the inventive method can be performed actively, for instance by ultraviolet radiation, especially with a customized or specific radiation profile / spectrum for optimum curing / solidification. Alternatively or additionally, the curing can happen rather passively by allowing the cooling of the cast substance purely due to a temperature difference between the cast substance and the environment. Typically, a two- component resin can be used as a cast substance which enables and / or facilitates the curing.

[0034] Between the third and fourth step of the inventive method or during the fourth step the cast substance can be given time to settle.

[0035] In an advantageous embodiment of the invention, the holder is manufactured by means of a three-dimensional printing technology, molding and casting using the same cast substance for the holder as the substance cast into the mould cavity in the third step, wherein the cured main body and the holder particularly have the same refractive index. As elucidated above, using the same substance for the manufacturing of the holder and the main body of the optical part is advantageous as - after curing - there will be no phase boundaries between the holder and the main body at which light could be disadvantageously reflected or scattered. This quasi-monolithic embodiment increases the optical performance of the optical part and therefore, if integrated into an optical system, also of the optical system. Furthermore, using the same 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 tension within the second optical element which might otherwise result in mechanical damage, such as cracks or ruptures within the second optical element. Preferably, the 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. The holder can be manufactured by firstly printing a master copy of the holder using an ultraviolet ink. Subsequently, a silicon mold can be manufactured. Finally, the holder can be cast into the silicon mold, wherein the cast substance can be a resin, particularly a two-component resin.

[0036] According to a preferred embodiment of the invention, - within the second step - the holder is placed into the mould cavity and the functional element is placed subsequently onto the holder. In other words, the holder and the functional element are placed separately and non- simultaneously into the mould cavity. It is also conceivable that the functional element is placed such into the mould cavity that the holder and the functional element are arranged in a coplanar manner. Also, the holder and the functional element can be placed into the mould cavity such that at least one holding arm can be arranged under the functional element and at least one other holding arm can be arranged over the functional element which results in the functional element being - so to say - clamped by holding arms.

[0037] In an advantageous embodiment of the invention, the functional element is connected to the holder by means of an optical bonding agent prior to putting the unit comprising the functional element and the holder into the mould cavity. The optical bonding agent can be a transparent material with the same refractive index as the holder substance. By means of an optical bonding agent reflection between two different phases, that is in the phase boundary, can be eliminated or at least reduced to a minimum, which results in an optimized optical performance of the optical system.

[0038] Preferably, the functional element is or comprises, at least substantially, a two-dimensional element, particularly a functional foil or a polarizer, wherein the substance is cast into the mould cavity by means of a special flow control ensuring that pressure on both sides of the functional element increases, at least substantially, simultaneously. A unilateral pressure increase can be due to the fact that one side of the functional element - inside the mould cavity - is being filled quicker than another side.

[0039] According to a preferred embodiment of the invention, the holder comprises at least one geometrical element, particularly a protrusion and / or a recess, and the mould comprises at least one complementary geometrical element, particularly a recess and / or a protrusion. The geometrical elements and the complementary geometrical elements are advantageous for leveling and positioning of the functional element. Furthermore, the geometrical elements and the complementary geometrical elements render the manufacturing more efficient as they act as self-aligning features. If necessary, protrusions can be easily trimmed off in case they extend beyond product boundaries, especially at a post-manufacturing point of time.

[0040] Another subject of the present invention is an optical part, particularly a lens for use in an augmented reality and / or virtual reality application, wherein the optical part comprises a main body and a functional element that is embedded into the main body, wherein the optical part comprises a holder for supporting, positioning and aligning the functional element.

[0041] The concept of the inventive optical part can be named an embedded concept. Such an embedded concept is an alternative for the abovementioned encapsulation concept of the three-piece optical system. One advantage of the optical part, that is of the embedded concept, is that it reduces the number of pieces and therefore material and an overall thickness. Therefore, the embedded concept can also reduce costs while maintaining structural integrity and hence mechanical stability. It is conceivable that the optical part serves as the second optical part in the abovementioned optical system. In other words, the embedded concept and the encapsulated concept can be combined which results in a hybrid concept.

[0042] According to a preferred embodiment of the invention, the main body, the functional element and the holder form a one-piece quasi-monolithic part. A one-piece quasi-monolithic part has the advantage of imperviousness or closeness. In other words, no solid or liquid or gaseous particles can enter the optical part, rendering the optical part particularly waterproof and dustproof, or the amount of entering particles can at least be reduced to a minimum. Quasi- monolithic within the meaning of the present invention is to be understood as seemingly monolithic, with substantially no gaps between the components of the optical part even though the optical part comprises different components.

[0043] In an advantageous embodiment of the invention, the holder and the main body are manufactured by the same substance, the holder and the main body particularly having the same refractive index. Using the same substance for the manufacturing of the holder and the main body is advantageous as there are 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 is that the functional element will appear to be freely suspended within the optical part. In areas where the holder is arranged, a high degree of clarity will be accomplished. Furthermore, using the same 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 tension within the optical part which might otherwise result in mechanical damage, such as cracks or ruptures. Preferably, the 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.

[0044] According to a preferred embodiment of the invention, the holder is a one-piece or multiplepiece element. The functional element can be connected and / or bonded unilaterally to a one- piece holder, thereby creating a holding unit. The holding unit then can be placed into a mould cavity and the main body substance of the second optical element can be cast until the main body is solidified / cured which results in the holding unit being embedded / incorporated partially or entirely within the main body of the second optical element. Also, the functional element can be connected and / or bonded to a multiple-piece, especially two-piece, holder. As a result, the functional element can be held and (mechanically) protected, for instance, bilaterally, for instance during the casting of the main body substance. As a result, the pressure on the functional element during the manufacturing process of the second optical element can be decreased and possible damages prevented. In case of a multiple-piece holder the single pieces can be connected to each other via snapping, clamping, bonding etc.

[0045] Preferably, the functional element is connected to the holder by means of an optical bonding agent. The optical bonding agent can be a transparent material with the same refractive index as the holder substance. By means of an optical bonding agent reflection between two different phases, that is in the phase boundary, can be eliminated or at least reduced to a minimum. Moreover, usage of an optical agent prevents possible air gaps between the holder and the functional element or reduces them at least to a minimum. As a result of one single substance for the holder and the functional element as well as of the prevention of air gaps an optimized optical performance of the optical system can be achieved.

[0046] According to an advantageous embodiment of the invention, the holder comprises at least one holding arm that is connected to the functional element. A holding arm can remove at least one degree of freedom. Increasing the number of holding arms can increase the stiffness of the functional element. Therefore, preferably, the functional element’s position is fixed by means of multiple holding arms. Moreover, the connection between the at least one holding arm and the functional element can be formed between a first end of the holding arm and an edge of the functional element (a quasi-point contact) or, alternatively, an area of the functional element formed at a frame section of the functional element can rest on a first end section of the holding arm (area contact). The at least one holding arm can be arranged perpendicularly to an edge of the functional element or an angle, preferably between 0° to 90°, can be formed between the holding arm and the functional element.

[0047] According to an advantageous embodiment of the invention, the functional element is or comprises, at least substantially, a two-dimensional element, particularly a functional foil or a polarizer. Preferably, the substantially two-dimensional functional element is arranged parallel to an outer surface of the second optical element. Preferably, the at least one holding arm is coplanar with the functional element. Alternatively - or in case of multiple holdings arms additionally - a main extension axis of at least one holding arm can be parallel to a main extension area of the functional element.

[0048] In an advantageous embodiment of the invention, the functional element comprises four edges, wherein at least one holding arm is connected to each of the four edges. Preferably, the functional element comprises a rectangular or quadratic contour. Each holding arm can be advantageously connected to one edge of the functional element, thereby creating a stiff functional element at a fixed position within the second optical element. Preferably, at least one pair of holding arms, each one of the two holding arms being connected to an opposing edge of the functional element, is arranged colinearly.

[0049] According to a preferred embodiment of the invention, the functional element comprises four corners, wherein at least one holding arm is connected to each of the four corners. Preferably, the holding arms are arranged symmetrically. In order to increase the stiffness of the functional element, especially during the manufacturing process, holding arms can be connected to the edges and to the corners of the functional element.

[0050] Preferably, the optical part comprises a concave eye-side surface and a convex world-side surface. The eye-side surface and the world-side surface can be formed parallel to each other. Adjacent to the eye-side surface, particularly between the eye-side surface and the functional element, an eye-side section can be formed that acts as an ophthalmic element with a specific eye-side diopter. Likewise, adjacent to the world-side surface, particularly between the world-side surface and the functional element, a world-side section can be formed that acts as an ophthalmic element with a specific world-side diopter. It is conceivable that the eye-side diopter and the world-side diopter add up to zero. In other words, the ophthalmic effect of the eye-side section that comprises the eye-side surface and the ophthalmic effect of the world-side section that comprises the world-side diopter can cancel each other out.

[0051] Two inventive optical parts can be used to form an optical system, especially an augmented reality or virtual reality headset, glasses or the like.

[0052] Features, technical effects, advantages and other characteristics of the inventive optical system, the inventive method and the optical part can be combined.

[0053] 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 example, 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.

[0054] Brief description of the drawings

[0055] Figure 1a illustrates schematically a first embodiment of an inventive holder in a top view.

[0056] Figure 1 b illustrates schematically a second embodiment of an inventive holder in a top view. Figure 1c illustrates schematically a third embodiment of an inventive holder in a top view.

[0057] Figure 1d illustrates schematically a fourth embodiment of an inventive holder in a top view.

[0058] Figure 2a illustrates schematically a fifth embodiment of an inventive holder in a top and a side view.

[0059] Figure 2b illustrates schematically a sixth embodiment of an inventive holder in a top and a side view.

[0060] Figure 3 illustrates schematically an embodiment of an inventive optical part in an embedded concept in a side view.

[0061] Figure 4 illustrates schematically another embodiment of an inventive optical part in a hybrid concept in a side view.

[0062] Detailed description

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The embodiments shown in the figures 1a to 1d illustrate an inventive optical system 1 that can be used in an encapsulation concept. However, the figures 1a to 1d also illustrate an inventive optical part 40 that can be used in an embedded concept.

[0067] Likewise, the holders 24 shown in the figures 2a and 2b and described hereinafter can be used in an optical system 1 as well as in an optical part 40. In figure 1a, a first embodiment of an inventive holder 24 is illustrated schematically in a top view. An optical system 1 , which can be an augmented reality or virtual reality headset or AR or VR suitable glasses in the following figures, comprises a first optical element 10, a second optical element 20 and a third optical element 30. The first optical element 10 and the third optical element 30 are ophthalmic elements and not visible in the figures. The first optical element 10 is a concave lens that is arranged such that when the glasses are put on the optical element 10 faces the human eye. The third optical element 30 on the other hand is a convex lens that is arranged such that when the glasses are put on the optical element 30 faces away from the human eye or faces the environment. The second optical element 20 is arranged between the first and the third optical element 10, 30. The three optical elements 10, 20, 30 are connected to each other in a stacked manner.

[0068] The second optical element 20 that is arranged in the middle of the stack of lenses comprises a functional element 22 that has a rectangular contour in the top view. According to the invention the second optical element 20 comprises the holder 24 for supporting, positioning and aligning the functional element 22.

[0069] The holder 24 comprises four holding arms 24’. Each holding arm 24’ is connected to an edge of the functional element 22. For this purpose, a respective first end of each holding arm 24’ is connected to a point of each edge of the functional element 22, wherein each point is arranged in the middle of the respective edge length. The connection between the holding arms 24’ and the functional element 22 is established by bonding, using an optical bonding agent. Two pairs of the holding arms 24’ are arranged colinearly.

[0070] Alternatively, the functional element 22 can be circular or comprise a section that is at least partially circular.

[0071] Figure 1a to figure 1d illustrate a second optical element 20 and an inventive optical part 40 whose manufacturing has been completed. In other words, the second optical element 20 (and therefore also the optical part 40) comprises a main body 26. The main body 26 is produced by casting and manufactured by a same transparent substance as the holder 24 and therefore also the four holding arms 24’. Therefore, the figures 1a to 1d are to be understood schematically since the holdings arms 24’ as well as the main body 26 are transparent. In other words, the holdings arms 24’ are, so to speak, invisible. There is no obvious phase boundary between the holding arms 24’ and the main body 26 and thus also no obvious reflection or scattering due to the same refractive indices of the functional element 22 and the holding arms 24’. Hence, the holdings arms 24’ and the main body 26 appear to be monolithic. The optical element 20 and the optical part 40 can be manufactured by providing a mould that comprises a mould cavity and subsequently placing the unit comprising the functional element 22 and the holding arms 24’ - that are already bonded to the functional element 22 - into the mould cavity. It is conceivable that the functional element 22 and the holding arms 24’ are placed into the mould cavity separately. Afterwards, the substance of the main body 26 that is the same substance of which the holding arms 24’ are manufactured is cast into the mould cavity. Finally, the cast main body 26 is cured. The holding arms 24’ shown in the figures 1a to 1d enable supporting, positioning and aligning of the functional element 22 before, during and after the casting of the main body 26. The main body 26 increases the mechanical support and stability of the functional element 22.

[0072] A frame section 28 of the second optical element 20 and / or the optical part 40 is shown to be circular. However, the shape of the frame section 28 is to be understood schematically as well. Every other shape, especially in conformity with conventional prescription glasses, is conceivable.

[0073] In figure 1b, a second embodiment of an inventive holder 24 is illustrated schematically in a top view. The holder 24 comprises eight holding arms 24’. A pair of holding arms 24’ is connected to respectively one of the four edges of the rectangular shaped functional element 22.

[0074] In figure 1c, a third embodiment of an inventive holder 24 is illustrated schematically in a top view. The functional element 22 has four corners. To each corner a holding arm 24’ is connected, thereby supporting, positioning and aligning the functional element 22. In the figures 1a and 1b all holding arms 24’ are arranged perpendicular to an edge of the functional element 22. In figure 1c on the other hand all holding arms 24’ are inclined relative to an edge of the functional element 22 and therefore arranged such that an angle between 0° and 90° is formed between each holding arm 24’ and an edge of the functional element 22. The holders 24 shown in the figures 1a to 1d are all symmetric holders.

[0075] In figure 1d, a fourth embodiment of an inventive holder 24 is illustrated schematically in a top view. The holder 24 comprises eight holding arms 24’. A pair of holding arms 24’ is connected to one respective corner of the functional element 22. The pair of holdings arms 24’ per corner are arranged perpendicularly to each other.

[0076] In figure 2a, a fifth embodiment of an inventive holder 24 is illustrated schematically in a top and a side view. On the left-hand side of figure 2a a top view of a one-piece holder 24 is shown. On the right-hand side of figure 2a a side view of the one-piece holder 24 is illustrated. The holder 24 comprises a planar section 24” serving as a substrate and an insertion section 24’” for inserting or placing the functional element 22 into it. The insertion section 24”’ is formed perpendicular to the planar section 24” and has a rectangular shape in the top view. The functional element 22 is placed or inserted into the insertion section 24”’ that comprises lateral walls / protrusions defining a precise position for the functional element 22.

[0077] In figure 2b, a sixth embodiment of an inventive holder is illustrated schematically in a top and a side view. On the left-hand side of figure 2b a top view of a two-piece holder 24 is shown. On the right-hand side of figure 2b a side view of the two-piece holder 24 is illustrated. Both views are schematic. The two pieces of the holder 24 can be connected to each other in various ways, for instance by means of a tight-fit or form-fit, by bonding them to each other by means of an optical bonding agent, by clamping one of them into the other or otherwise or a combination thereof. The functional element 22 can be inserted in-between of the of protruding walls of the insertion section 24’”. An embodiment as shown in figure 2b has the advantage of multi-laterally protecting the functional element 22 against excessive pressures, for instance during the casting of the main body substance 26 into a mould. In addition to positioning and aligning, the two-piece holder 24 offers higher mechanical support for the functional element 22.

[0078] It is also conceivable that the protruding walls of the insertion section 24’” comprise - in a top view as visible in figure 2a - an inner shape and an outer shape, wherein the inner shape is different than the outer shape of the walls. The inner shape can be, for instance, rectangular for an optimal form-fit of the functional element, while the outer shape of the walls can be circular or elliptic. Between the inner shape and the outer shape, the walls can be massive or solid. But it is also conceivable that the walls are two-layered, meaning that two walls are formed such that they comprise a common center of gravity which also corresponds to the center of gravity of the functional element 22. In other words, the two walls, the first comprising the inner shape and the second comprising the circular or elliptic shape, can be spaced apart, forming a hollow space between them.

[0079] Figure 3 illustrates schematically an embodiment of an inventive optical part 40 in an embedded concept in a side view. The optical part 40 is a lens for use in an augmented reality and / or virtual reality application. It comprises a main body 26 and a functional element 22 that is fully embedded into the main body 26. The optical part 40 further comprises a holder 24 for supporting, positioning and aligning the functional element 22. The main body 26, the functional element 22 and the holder 24 form a one-piece quasi-monolithic part.

[0080] Furthermore, the holder 24 and the main body 26 are manufactured by the same substance, the holder 24 and the main body 26 particularly having the same refractive index. Using the same substance for the manufacturing of the holder 24 and the main body 26 is advantageous as there are no phase boundaries between the holder 24 and the main body 26 at which light could be disadvantageously reflected or scattered. The holder is, so to say, invisible. In other words, a technical effect of such an embodiment is that the functional element 22 will appear to be freely suspended in the optical part 40. The optical clarity is indicated to or implied by the dashed arrow on the left-hand side of figure 3.

[0081] The optical part 40 comprises a concave eye-side surface 44 and a convex world-side surface 42. The specific embodiment shown schematically in figure 3 is such that a cumulative or overall diopter of the optical part 40 is zero. However, it is also conceivable that the cumulative or overall diopter of the optical part 40 amounts to a different value than zero, for instance 1.0, 3.5, -2.8 or any other positive or negative value.

[0082] Figure 4 illustrates schematically another embodiment of an inventive optical part 40 in a hybrid concept in a side view. According to the hybrid concept, an inventive optical part 40 that serves as a second optical element 20 within an optical system 1 is encapsulated between and / or within a first optical element 10 and a third optical element 30.

[0083] One advantage of the optical part 40 in an embedded concept over a purely encapsulation concept, wherein particularly a waveguide rather than an inventive optical part 40 is encapsulated, is that the optical part 40 reduces the number of pieces and therefore material and an overall thickness. Therefore, the embedded concept can also reduce costs while maintaining structural integrity and hence mechanical stability.

[0084] List of reference signs

[0085] 1 Optical system

[0086] 10 First optical system

[0087] 20 Second optical system 22 Functional element

[0088] 24 Holder

[0089] 24’ Holding arm

[0090] 24” Planar section of the holder

[0091] 24”’ Insertion section 26 Main body of the second optical element

[0092] 28 Frame section of the second optical element

[0093] 30 Third optical system

[0094] 40 Optical part

[0095] 42 World-side surface 44 Eye-side surface

Claims

PATENT CLAIMS1. Optical system (1), particularly for an augmented reality and / or virtual reality application, with a first optical element (10), a second optical element (20) and a third optical element (30), wherein the first optical element (10) and the third optical element (30) are ophthalmic elements, wherein the second optical element (20) is arranged, at least partially, between the first optical element (10) and the third optical element (30), and wherein the second optical element (20) comprises a functional element (22), characterized in that the second optical element (20) comprises a holder (24) for supporting, positioning and aligning the functional element (22).

2. Optical system (1) according to claim 1, wherein the holder (24) and a main body (26) of the second optical element (20) are manufactured by the same substance, the main body and the holder (24) particularly having the same refractive index.

3. Optical system (1) according to any one of the preceding claims, wherein the holder (24) is a one-piece or multiple-piece element.

4. Optical system (1) according to any one of the preceding claims, wherein the functional element (22) is connected to the holder (24) by means of an optical bonding agent.

5. Optical system (1) according to any one of the preceding claims, wherein the holder (24) comprises at least one holding arm (24’) that is connected to the functional element (22).

6. Optical system (1) according to any one of the preceding claims, wherein the functional element (22) is or comprises, at least substantially, a two-dimensional element, particularly a functional foil or a polarizer.

7. Optical system (1) according to claim 5 or 6, wherein the functional element (22) comprises four edges, wherein at least one holding arm (24’) is connected to each of the four edges.

8. Optical system (1) according to claim 5 or 6, wherein the functional element (22) comprises four corners, wherein at least one holding arm (24’) is connected to each of the four corners.

9. Method for manufacturing an optical part (40), particularly for an augmented reality and / or virtual reality application, wherein in a first step a mould comprising a mould cavity is provided,in a second step a functional element (22) and a holder (24) are placed into the mould cavity, in a third step a substance is cast into the mould cavity, and in a fourth step the cast substance is cured such that it - after having cured - forms a main body of the optical part (40), wherein the optical part (40) comprises the main body, the functional element (22) and the holder (24).

10. Method according to claim 9, wherein the holder (24) is manufactured by means of a three-dimensional printing technology, molding and casting using the same cast substance for the holder (24) as the substance cast into the mould cavity in the third step, wherein the cured main body and the holder (24) particularly have the same refractive index.

11. Method according to claim 9 or 10, wherein - within the second step - the holder (24) is placed into the mould cavity and the functional element (22) is placed subsequently onto the holder (24).

12. Method according to claim 9 or 10, wherein the functional element (22) is connected to the holder (24) by means of an optical bonding agent prior to putting the unit comprising the functional element (22) and the holder (24) into the mould cavity.

13. Method according to any of the claims 9 to 12, wherein the functional element (22) is or comprises, at least substantially, a two-dimensional element, particularly a functional foil or a polarizer, wherein the substance is cast into the mould cavity by means of a special flow control ensuring that pressure on both sides of the functional element (22) increases, at least substantially, simultaneously.

14. Method according to any of the claims 9 to 13, wherein the holder (24) comprises at least one geometrical element, particularly a protrusion and / or a recess, and the mould comprises at least one complementary geometrical element, particularly a recess and / or a protrusion.

15. Optical part (40), particularly a lens for use in an augmented reality and / or virtual reality application, wherein the optical part (40) comprises a main body (26) and a functional element (22) that is embedded into the main body (26), characterized in that the optical part (40) comprises a holder (24) for supporting, positioning and aligning the functional element (22).

16. Optical part (40) according to claim 15, wherein the main body (26), the functional element (22) and the holder (24) form a one-piece quasi-monolithic part.

17. Optical part (40) according to claim 15 or 16, wherein the holder (24) and the main body (26) are manufactured by the same substance, the holder (24) and the main body (26) particularly having the same refractive index.

18. Optical part (40) according to any of the claims 15 to 17, wherein the holder (24) is a one-piece or multiple-piece element.

19. Optical part (40) according to any of the claims 15 to 18, wherein the functional element (22) is connected to the holder (24) by means of an optical bonding agent.

20. Optical part (40) according to any of the claims 15 to 19, wherein the holder (24) comprises at least one holding arm (24’) that is connected to the functional element (22).

21. Optical part (40) according to any of the claims 15 to 20, wherein the functional element (22) is or comprises, at least substantially, a two-dimensional element, particularly a functional foil or a polarizer.

22. Optical part (40) according to claim 20 or 21, wherein the functional element (22) comprises four edges, wherein at least one holding arm (24’) is connected to each of the four edges.

23. Optical part (40) according to claim 20 or 21, wherein the functional element (22) comprises four corners, wherein at least one holding arm (24’) is connected to each of the four corners.

24. Optical part (40) according to any of the claims 15 to 23, wherein the optical part (40) comprises a concave eye-side surface and a convex world-side surface.

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