Method of producing an optical arrangement and optical arrangement

Abstract

To produce an optical arrangement (10) comprising a first optical component (12) having a first surface (18) and a second optical component (14) having a second surface (20) integrally connected to the first surface (18) except for at least one gap region (16) having at least one gap between the first and second surfaces (18, 20), the first optical component (12) is provided, the first surface (18) of the first optical component (12) is surface treated in one or more predefined regions (22, 22a) of the first surface (18) to change a surface energy of the first surface (18) in said one or more predefined regions (22, 22a), the second optical component (14) is provided with the second surface (20) integrally connected to the first surface (18) of the first optical component (12) by means of direct contact or through a continuous layer of adhesive (24), and a pre-defined time is waited for creating the at least one gap region (16) having at least one gap between the first and second surfaces (18, 20) by delamination of a material of the second optical component (14) or the adhesive (24) from the first surface (18) in said one or more predefined regions (22, 22a)

Description

Method of producing an optical arrangement and optical arrangement

[0001] The invention relates to a method of producing an optical arrangement comprising a first optical component having a first surface and a second optical component having a second surface integrally connected to the first surface except for at least one gap region having at least one gap between the first and second surfaces . The invention further relates to a corresponding optical arrangement, in particular for a head-mounted display.

[0002] An optical arrangement according to the present invention may comprise two or more than two optical components in a stacked arrangement, with or without additional gap regions between adjacent surfaces of the optical components.

[0003] In the context of the present invention, the "gap region" may be a gap filled with natural air, however it could also be filled with any gaseous fluid different from natural air, and even a gap void of matter, i.e. a vacuum or at least a partial vacuum is encompassed by the present invention.

[0004] An optical arrangement according to the present invention may be used in head-mounted displays, as comprised by data glasses, augmented-reality headsets, virtual-reality headsets, mixed-reality headsets or augmented-reality, virtual-reality or mixed-reality glasses, etc. Head-mounted displays (HMDs) or near-eye-displays (NEDs) typically comprise an image generator or projector system and an optical arrangement to transmit image light generated by the projector system to a user's eye. The optical arrangement typically comprises a waveguide with an in-coupling structure and an out-coupling structure. The waveguide is designed to guide the image light coupled-in at the in-coupling structure by total internal reflections to the out-coupling structure where the image light is output-coupled towards an eye of the user. The waveguide has to be placed in conditions that do not degrade total internal reflections of light waves inside the waveguide, i.e. inbetween its dedicated surfaces that consist of providing a large enough change of refractive index at the dedicated surfaces of the waveguide. The large enough change of refractive index is advantageously provided by a gap region around the dedicated surfaces of the waveguide or a waveguiding part of the waveguide for enabling total internalreflections of the guided light inside the dedicated waveguiding part or parts of the waveguide.

[0005] In order to provide smart glasses with a correction of vision defects / vision impairment of a user, i.e. prescription-enabled smart glasses, it is known to use an optical arrangement, where the waveguide, such as a planar waveguide, is supplemented with a prescription (Rx) lens or lenses arranged across a field of view of the user. In other words, such optical arrangements may include a stacked structure of a waveguide and Rx lens or lenses. However, it may be technically difficult to produce a stacked optical arrangement with a gap region in a predefined region between the mutually facing surfaces of the optical elements with low production complexity and costs.

[0006] WO 2024 / 008593 A1 discloses a method for producing an optical arrangement comprising an optical waveguide and a lens in a stacked arrangement with a gap region between the waveguide and the lens. This known method requires a mask to be applied to the waveguide or the lens before applying an adhesive used for bonding the waveguide and lens to each other. The mask must be removed after hardening of the adhesive and bonding of the elements to each other which makes the removal complicated and could lead to a break of the mask, deformation of the mask or contamination of the mask. Thereby, the mask is an additional, single-use element to be manufactured separately that further requires a high-precision application and a complicated removal by means of different technological processors as compared to the adhesive deposition. The production process thus becomes more complicated and expensive.

[0007] US 11 243 398 B2 discloses an optical arrangement usable in a head-mounted display. The optical arrangement comprises an optical waveguide having two opposite main faces for conducting light by total internal reflection, and at least one wafer facing one of the surfaces of the waveguide. Interposition means is provided in contact with said surface of the light conducting element and defines a gap optically isolating the waveguide.

[0008] US 10288 907 B2 discloses a method for producing an optical arrangement comprising a waveguide and an Rx lens, wherein no gap region is provided and the lens body is molded directly around the waveguiding insert.

[0009] WO 2016 / 075689 A1 discloses the application of a moth-eye or air gap film to provide the required gap.

[0010] US 20240142694 A1 discloses a stacked optical assembly comprising a first optical substrate, a second optical substrate and micro spacers positioned between the first and second optical substrates for maintaining a gap therebetween. The micro spacers can comprise layers of cured resin material formed by a 3D printing process, preferably, such that each layer is cured from a single droplet of the resin material. Such a gap-enabling technique provides for a compact and lightweight stacked optical assembly, but it is complicated and expensive.

[0011] Thus, most of the known solutions require additional means and techniques to provide the desired gap region in a desired area of an optical arrangement, the additional means and techniques leading to increased complexity and costs of the optical arrangement production. Molding or casting of a lens body around a waveguide would be the most advantageous technique, in terms of both cost and complexity of the production process, but up to now it does not allow a controllable embedding of a gap region into the molded or casted structure.

[0012] It is an object of the present invention to provide a method of producing an optical arrangement which provides a simple and effective technique for producing a stack of optical components, preferably a waveguide and a lens, with a controlled gap region inbetween them in a desired region of the stack structure.

[0013] It is a further object of the present invention to provide a corresponding optical arrangement, in particular for a head-mounted display.

[0014] According to a first aspect of the invention, a method of producing an optical arrangement is provided, the optical arrangement comprising a first optical component having a first surface and a second optical component having a second surface integrally connected to the first surface except for at least one gap region having at least one gap between the first and second surfaces, the method comprising: providing the first optical component; surface treating the first surface of the first optical component in one or more predefined regions of the first surface to change a surface energy of the first surface in said one or more predefined regions; providing the second optical component with the second surface integrally connected to the first surface of the first optical component by means of direct contact or through a continuous layer of adhesive; and waiting for a pre-defined time for creating the at least one gap region having at least one gap between the first and second surfaces by delamination of a material of the second optical component or the adhesive from the first surface.

[0015] The invention proposes, prior to integrally connecting the second surface of the second optical component to the first surface of the first optical component by means of direct contact or through a continuous layer of adhesive, a surface treatment of the first surface of the first optical component in one or more predefined regions of the first surface to provide a change in surface energy in that one or more predefined regions. The surface treatment may be selected or configured to lower the surface energy of the first surface of the first optical component in the treated pre-defined region(s) so that the first surface of the first optical component becomes repellent to the adhesive or the material of the second optical component in the surface treated region(s) (in the following briefly referred to as the repelling treatment), or the surface treatment may be selected or configured such that it raises the surface energy in the treated pre-defined region(s) so that the first surface of the first optical component becomes wettable to the adhesive or the material of the second optical component (in the following briefly referred to as the wetting treatment) in the surface treated pre-defined region(s). If the surface treating creates a repelling effect, the adhesive or the material of the second optical component will, after waiting a pre-defined time, delaminate from the first surface in the pre-defined surface treatedregion(s), and thus one or more gap regions is / are created in that predefined region(s). If the surface treating creates a wetting effect, the adhesive or the material of the second optical component will delaminate, after a pre-defined time, in a region or regions outside the surface treated pre-defined regions, and thus one or more gap regions is / are created in said region(s) outside the surface treated regions.

[0016] The step of waiting for a pre-defined time for creating the gap(s) may comprise heating the optical arrangement to promote or accelerate shrinkage and thus delamination of the adhesive or the material of the second optical arrangement from the first surface.

[0017] Typically, adhesive materials or molten materials shrink during solidification or due to applying energy, for example when an adhesive material is cured by UV light and / or when heat is applied, or when a molten material is cooled down. Shrinkage of the adhesive or the molten material leads to a delamination of the adhesive or molten material from the surface or surfaces where it is applied. Without the surface treatment as provided by the present invention, delamination is not controllable, i.e. delamination may occur in regions where delamination is not desired and delamination may not occur in regions where it is desired. In contrast, with the surface treatment which increases or lowers the surface energy, delamination occurs in a controlled manner in region(s) of the stacked structure, where delamination is desired to create the gap region.

[0018] Thus, by virtue of the present invention, one or more gap regions may be created in a controllable manner due to the surface treatment of the first surface of the first component prior to the process of integrally connecting the second surface of the second optical component to the first surface of the first optical component. Further, no additional technical means or techniques are required to provide the desired gap region in a desired area of the optical arrangement.

[0019] It is to be understood that the surface treatment may comprise only a repelling treatment in one or more predefined regions, or only a wetting treatment in one or more other predefined regions, or may be a combination of the repelling treatment in one or more first predefined regions and the wetting treatment in one or more second predefined regions,wherein the second predefined regions are different or separated from the first predefined regions.

[0020] The at least one gap region created by the method according to the invention may have a height from the surface of the first optical component, which is as small as a few micrometers to several hundreds of micrometers. Such a height is sufficient to provide for the conditions of total internal reflection for light in the visible spectrum.

[0021] Embodiments of the method according to the invention will be described in the following.

[0022] In an embodiment, the surface treating is configured to enhance a repelling effect on the first surface, and the surface treating is performed in at least one first predefined region of the first surface which corresponds to the at least one gap region to be created.

[0023] In this embodiment, the adhesive or the material of the second optical component will delaminate in defined manner from the first surface in the region(s) of the surface in which the repelling treatment has been performed, so as to create the gap region in that predefined region of the surface treating.

[0024] In another embodiment, the surface treating is configured to enhance a wetting effect on the first surface, and the surface treating is performed in at least one second predefined region which is outside the at least one gap region.

[0025] The wetting treatment of the first surface in one or more predefined regions results in an enhanced and accelerated abutting and bonding of the adhesive or the material of the second optical component in said one or more surface treated pre-defined regions, while the absence of the wetting treatment in other regions, in particular in a region where the gap region is to be formed, may lead to a lack of close contact when the optical components are successfully connected. That is, in the region where the at least one gap is to be created, there is no enhanced wetting effect so that the adhesive or the material of the second optical component can delaminate from the first surface in this or these regions to create the at least one gap region.

[0026] As described above, the method may include only one type of surface treating of the surface of the first optical component, i.e. either a surface treating which enhances a repelling effect, or a surface treating, which enhances a wetting effect.

[0027] In another embodiment, it may be advantageous, when the surface treating comprises a first surface treating configured to enhance a repelling effect on the first surface, and the first surface treating is performed in at least one first predefined region of the first surface that corresponds to the gap region to be created, and the surface treating further comprises a second surface treating configured to enhance a wetting effect on the first surface, and the second surface treating is performed in at least one second predefined region outside the gap region to be created.

[0028] This embodiment is advantageous, because the wetting treatment enhances and accelerates abutting and bonding the first and second surfaces in the second predefined region or regions outside the at least one gap region, while the repelling treatment in the at least one gap region to be created accelerates the delamination of the adhesive or the material of the second optical component from the first surface and thus accelerates creation of the desired at least one gap region in controlled manner in the desired position.

[0029] In the context of the previous embodiments, the second predefined region may be the whole or substantially the whole area of the first surface except of the at least one gap region.

[0030] In this embodiment, a durable and reliable connection of the first and second optical components to each other may be ensured.

[0031] In a further embodiment, the providing of the second optical component comprises bonding the second surface to the first surface using the continuous layer of the adhesive, wherein the surface treating is configured to enhance a repelling effect or a wetting effect on the first surface with respect to the adhesive.

[0032] According to this embodiment, the optical arrangement is produced by bonding the premanufactured first and second optical components to each other using an adhesive. Bonding the optical components using an adhesive (in the following briefly referred to as the bonding process) may be performed by any conventional technique.

[0033] In the context of the previous embodiment, i.e. in case of bonding the first and second optical components to each other by using an adhesive, a further embodiment provides that the method further comprises, before the bonding, surface treating the second surface of the second optical component in one or more predefined regions of the second surface, wherein the surface treating of the second surface is configured to enhance a repelling effect or a wetting effect with respect to the adhesive.

[0034] In particular in case of the repelling treatment, this embodiment is advantageous as it strengthens the repelling effects in the gap region to be created during the bonding of the optical components to each other and ensures a desired height and shape of the resultant gap region.

[0035] It is to be understood that a plurality of gap regions may be created by the method according to the invention by applying the surface treatment in a plurality of regions of the first optical component and / or second optical component to create one or more gap regions.

[0036] Further in the context of the previous embodiments related to the bonding process, in a further embodiment, the method further comprises: selecting the surface treatment and / or the surface treatment parameters with reference to shrinkage characteristics of the adhesive to enable the delamination of the adhesive in the one or more predefined regions during solidification or thermal shrinkage of the adhesive, and / or adjusting the shrinkage characteristics of the adhesive with reference to the selected surface treatment and / or the surface treatment parameters.

[0037] According to this embodiment, the surface treatment and / or the surface treatment parameters may be configured or selected with reference to either the shrinkage charac-teristics of the adhesive material to be used for bonding the first and second optical components. In addition or alternatively, the shrinkage characteristics of the adhesive can be adjusted with reference to the selected surface treatment and / or the surface treatment parameters so that to provide the required gap region. The shrinkage characteristics of the adhesive can be adjusted, for example, by means of specific additives to the adhesive used in the bonding process , and / or by adjusting the applicable process parameters, such as one or more of pressure, time, temperature during at least a part of the bonding process.

[0038] In a further embodiment, as an alternative to the bonding process described before, the providing of the second optical component comprises creating the second optical component by molding or casting the second optical component from a molten material or curable material onto at least a part of the first surface of the first optical component, wherein the surface treating is configured to enhance a repelling effect or a wetting effect on the first surface with respect to the molten material or curable material of the second optical component, and the pre-defined time comprises a time of solidification of the molten material or curable material.

[0039] In this embodiment, the optical arrangement is produced by providing the premanufactured first optical component, and creating the second optical component by molding or casting the second optical component from a molten material or curable material onto at least a part of the first surface of the first optical component. Mold- ing / casting the second optical component onto the first optical component (in the following briefly referred to as the molding process), may be a conventional technique. In case of molding the second optical component from a molten material, the second optical component may be created around or in connection with the first optical component, e.g. by means of injection molding so that the mutually facing surfaces of the first optical component and the second optical component are integrally connected to each other in one or more regions of the mutually facing surfaces. For example, the first optical component may be inserted into a mold while the second optical component is created by molding therein, such as by injection molding, i.e. by injecting a molten material of the second optical component into the mold so that in result at least a part of the first optical component is embedded into the second optical component. The molten material may be athermoplastic material in case of molding the second optical component, while a thermosetting material may be preferred in case of casting the second optical component.

[0040] If the surface treating of the first surface of the first optical component creates a repelling effect, the molten material or curable material of the second optical component will, after a pre-defined time, which is the time of solidification of the molten material, delaminate from the first surface in the pre-defined surface treated region(s), and thus one or more gap regions is / are created in that predefined region(s). If the surface treating creates a wetting effect, the molten material or curable material of the second optical component will delaminate, after a pre-defined time, in a region or regions outside the surface treated predefined regions, and thus one or more gap regions is / are created in said region(s) outside the surface treated regions.

[0041] In the context of the previous embodiment relating to the molding / casting process, in a further embodiment the method further comprises: selecting the surface treatment and / or the surface treatment parameters with reference to shrinkage characteristics of the molten material or curable material to enable the delamination of the molten material in the one or more predefined regions during solidification or thermal shrinkage of the molten material or curable material, and / or adjusting the shrinkage characteristics of the molten material or curable material with reference to the selected surface treatment and / or the surface treatment parameters.

[0042] According to this embodiment, the surface treatment and / or the surface treatment parameters may be configured or selected with reference to either the shrinkage characteristics of the molten material or curable material to be used for molding / casting the second optical component around or in connection with the first optical component. In addition or alternatively, the shrinkage characteristics of the molten material or curable material can be adjusted with reference to the selected surface treatment and / or the surface treatment parameters so that to provide the required gap region. The shrinkage characteristics of the molten material or curable material can be adjusted, for example, by means of specific additives to the molten material or curable material used in the molding / casting process.

[0043] In further embodiments, the surface treating comprises one or more of the following: plasma treating, coating, surface grafting, acid etching, mechanical surface processing.

[0044] The mechanical surface processing may comprise scratching the surface. Scratching is usually designed to increase a surface roughness.

[0045] Surface grafting is a technique in polymer chemistry and refers to the addition of polymer chains onto a surface.

[0046] In further embodiments, the first optical component is one of an optical waveguide and a lens, and the second optical component is another one of the optical waveguide and the lens.

[0047] According to a further aspect, an optical arrangement for a head-mounted display is provided, the optical arrangement being produced by a method according to the first aspect.

[0048] According to a further aspect of the present invention, an optical arrangement is provided, comprising a first optical component having a first surface and a second optical component having a second surface integrally connected to the first surface except of at least one gap region having at least one gap where a material of the second optical component is delaminated from the first surface.

[0049] According to a further aspect of the present invention, an optical arrangement is provided, comprising a first optical component having a first surface and a second optical component having a second surface integrally connected to the first surface through a continuous layer of adhesive except of at least one gap region having at least one gap where the adhesive is delaminated from the first surface and / or the second surface.

[0050] It would be appreciated by those skilled in the art that the optical arrangements according to the invention may have the corresponding embodiments and provide the same advantages as the method according to the invention.

[0051] It is to be understood that the invention is advantageous in the production of stacked optical structures with one or more gap regions in the stack structure independent of the type of optical components the stack structure comprises.

[0052] Further features and advantages will become apparent from the following description and the drawings.

[0053] Preferred embodiments of the invention are shown in the drawings and will be described below with reference to the drawings. In the drawings:Fig. 1 shows a cross-section of an optical arrangement in a semiassembled state according to an embodiment of a method of producing the optical arrangement;Fig. 2 shows a cross-section of an optical arrangement in a semiassembled state according to another embodiment of a method of producing the optical arrangement;Fig. 3 shows a cross-section of an optical arrangement in a semiassembled state according to yet another embodiment of a method of producing the optical arrangement;Fig. 4 shows a cross-section of an optical arrangement made by a molding process according to another embodiment of a method of producing the optical arrangement;Fig. 5A and Fig. 5B show a cross-section of an optical arrangement in initial and final states of a bonding process according to another embodiment of a method of producing the optical arrangement; andFig. 6A and 6B show a cross-section of an optical arrangement in initial and final states of a bonding process according to yet another embodiment of a method of producing the optical arrangement.

[0054] Preferred embodiments of the invention will now be described with reference to Fig. 1 to 6. Elements which are identical, similar or comparable among the embodiments shown in Fig. 1 to 6 are labeled with the same reference numerals.

[0055] Fig. 1 shows a cross-section of an optical arrangement labelled with general reference numeral 10. The optical arrangement 10 comprises an optical component 12 and an optical component 14. The term "first optical component" as used in the claims may refer to the optical component 12, and the term "second optical component" as used in the claims may refer to the optical component 14, or the term "first optical component" as used in the claims may refer to the optical component 14, and the term "second optical component" as used in the claims may refer to the optical component 12.

[0056] The optical components 12 and 14 may be any type of optical components. The optical component 12 may be an optical waveguide, and the optical component 14 may be a lens, e.g. an Rx lens (prescription lens). It is to be understood that in other embodiments the optical component 12 may be a lens, e.g. an Rx lens, and the optical component 14 may be a waveguide. It is also possible that the optical components 12 and 14 are both waveguides, or both lenses, etc. For simplicity of the drawings and the following description and without limiting the scope of the invention, the optical component 12 will also be referred to as an optical waveguide, and the optical component 14 will also be referred to as a lens.

[0057] In an embodiment of a method of producing the optical arrangement 10 according to the invention, the optical component 12 and the optical component 14 are to be connected to each other in a stacked arrangement with a gap region 16 of longitudinal dimension L between mutually facing surfaces 18 and 20 of the optical component 12 and the optical component 14. Fig. 1 shows the optical components 12 and 14 before being connected to each other.

[0058] The surface 18 of the optical component 12 may be planar. The surface 20 of the optical component 14 may be planar as well, without limiting the invention to optical components having planar surfaces.

[0059] In embodiments of the method of producing the optical arrangement 10, the optical components 12 and 14 can be connected to each other at the surfaces 18 and 20 in different ways. In a first way, the optical component 12 and the optical component 14 are provided as pre-manufactured optical components.

[0060] In one embodiment, the optical component 14 is provided with the surface 20 integrally connected to the surface 18 of the optical component 12 through a continuous layer of adhesive. In this embodiment, the surface 20 of the optical component 14 is bonded to the surface 18 of the optical component 12 with an adhesive (not shown in Fig. 1). This type of process, by which the optical components 12 and 14 are joined to each other to form a stacked optical arrangement, is referred to in the present disclosure as the bonding process.

[0061] Alternatively, in another embodiment, the optical component 14 is provided with the surface 20 integrally connected to the surface 18 of the optical component 12 by means of direct contact. In this embodiment, only the optical component 12 is provided as a premanufactured optical component, and the optical component 14 is created by molding or casting the optical component 14 from a molten material or curable material onto at least a part of the surface 18 of the optical component 12. This type of process, by which the optical components 12 and 14 are joined to each other to form a stacked optical arrangement, is referred to in the present description as the molding process. In case of molding the optical component 14, the optical component 14 may be created around or in connection with the optical component 12 by means of injection molding so that the surfaces 18, 20 are at least partially connected to each other. For example, the optical component 12 may be inserted into a mold while the optical component 14 is created by molding such as by injection molding, i.e. by injecting a molten material of the optical component 14 into the mold so that in result at least a part of the optical component 12 is embedded into the optical component 14, as, for example, shown in Fig. 4. In case of molding, the opticalcomponent 14 may be created from a thermoplastic material, and in case of casting from a thermosetting material.

[0062] When producing the optical arrangement 10, i.e. combining the optical components 12 and 14 to a stack structure, regardless whether using the bonding process or the mold- ing / casting process (molding / casting process will be briefly referred to as the molding process in the present description), the gap region 16 is to be created in a defined desired position and in a controllable manner. The gap region 16, which may be an air gap, or in general a fluid gap or a vacuum gap, shall ensure maintaining the conditions for total internal reflection of light propagation within the optical component 12, e.g. in case the optical component 12 is an optical waveguide. The region where the gap is to be created (the gap region 16) is also referred to as the target region 22 shown in Figs. 1 to 6 by a rectangle in broken lines.

[0063] In order to enable creating the gap region in controlled manner in a desired defined position, the invention proposes a surface treatment of one or both of the surfaces 18, 20 in one or more predefined regions prior to the bonding or molding process. The surface treatment is configured or selected to provide for a change in a surface energy in one or more predefined regions of the surface 18 and / or the surface 20 of the to-be contacting surfaces 18, 20 of the optical components 12, 14. Especially, the surface treatment is configured or selected to enhance a wetting effect of the surface 18 and / or 20 in said one or more predefined regions, i.e. enhances the capability of the surface 18 and / or 20 to be wetted by the adhesive or molten material during the bonding or molding process, or to enhance a repelling effect of the surfaces 18 and / or 20 in said one or more predefined regions, i.e. enhances the capability of the surface 18 and / or 20 in said one or more predefined regions to repel the adhesive or molten material during the bonding or molding process.

[0064] In Fig. 1 , the target region 22 is a predefined region of the surface 18 of the optical component 12. The target region 22 is a region where the gap 16 (an air gap or a vacuum gap) is to be provided after the bonding or molding process. In an embodiment, the target region 22 is subject to a surface treatment which lowers the surface energy in the target region 22 of the surface 18, i.e. the surface treatment enhances a repelling effect (alsoreferred to as the repelling treatment) so that the introduced repelling effect, as itself or in combination with shrinkage characteristics of an adhesive material in case of the bonding process or of a molten material of the optical component 14 in case of the molding process, prevent a close contact of the adjacent surfaces 18, 20 of the optical components 12, 14 in the target region 22 and instead provide for an air gap in the target region 22 by delamination of the adhesive or of the molten material from the surface 18, when the adhesive or the molten material are solidified after a pre-defined waiting time. In case of the bonding process, the pre-defined waiting time is the time the adhesive needs to cure, e.g. by using ultraviolet (UV) light. In case of the molding process, the pre-defined waiting time is the time the molten material needs to solidify.

[0065] In regions 26 and 28 outside the gap region 16 to be created, there may be no surface treatment, while in other embodiments described below, there may be performed a wetting treatment. The same holds for the embodiments in Fig. 2 to 6, in which the regions 26 and 28 outside the target region 22 may be not surface treated or treated by a wetting treatment.

[0066] Fig. 2 shows another embodiment, in which the target region 22 where the gap region 16 is to be created, is provided on the surface 20 of the optical component 14. The embodiment of Fig. 2 relates to the bonding process only, as the surface treatment of the surface 20 of the optical component 14 can only be performed when the optical component 14 is provided as a pre-manufactured optical component.

[0067] It is to be understood that there may be a plurality of target regions 22 along the surface 18 and / or along the surface 20 that are subject to a surface treatment, in particular a repelling treatment, to provide a plurality of gaps in said predefined regions.

[0068] In general, the surface treatment and / or the surface treatment parameters may be configured or selected with reference to the shrinkage characteristics of the adhesive material in case of the bonding process or of the material of the optical component 14 in case of the molding process, and / or the shrinkage characteristics of the adhesive in case of the bonding process or of the molten material in case of the molding process can beadjusted with reference to the selected surface treatment and / or the surface treatment parameters so as to provide the required gap through a controlled delamination of the adhesive material or the molten material during solidification.

[0069] Fig. 3 shows an embodiment, in which both surfaces 18 and 20 of the optical components 12 and 14 are surface-treated in target regions 22a and 22b, where the gap region 16 is to be created. The surface treatment is configured or selected to enhance a repelling effect in the target regions 22a and 22b of the surfaces 18 and 20. This embodiment is advantageous as the repelling effects and thus the delamination of the adhesive from the surface 18 after solidification can be strengthened in the target regions 22a and 22b after the bonding of the optical components 12 and 14 to each other and ensure a desired height and shape of the resultant gap.

[0070] Fig. 4 shows an embodiment in which the optical arrangement 10 is produced by molding the optical component 14 from a molten material onto the surface 18 of the optical component 12. In the embodiment of Fig. 4, the optical component 12 is embedded in the optical component 14. In this embodiment, the target region 22, in which the gap region 16 is to be created, is subject to a surface treatment configured or selected to enhance a repelling effect causing the molten material for creating the optical component 14 to be repelled by the surface 18 of the optical component 12 so that, during solidification of the molten material, the surface of the optical component 14 which faces the surface 18, delaminates from the surface 18. Again, the surface treatment and / or the surface treatment parameters may be configured or selected with reference to the shrinkage characteristics of the molten material used for creating the optical component 14 during solidification of the molten material, and / or the shrinkage characteristics of the molten material can be adjusted with reference to the selected surface treatment and / or the surface treatment parameters so as to provide the required gap 16 through a controlled delamination during solidification of the molten material. A further gap region opposite the gap region 16 on the side of the surface 18 may be created on the surface 21 opposite the surface 18 of the optical component 12 by providing a corresponding surface treatment, in particular a repelling treatment of that surface.

[0071] While in the embodiments described above with reference to Figs. 1—4, the surface treatment is configured or selected to enhance a repelling effect of the surface 18 and / or the surface 20 in the target region 22, it is also possible to alternatively or in addition subject the surface 18 and / or 20 in regions 26 and 28 outside the target region 22 to a surface treatment which enhances a wetting effect with respect to the adhesive in case of the bonding process or with respect to the molten material in case of the molding process. That is, a surface treatment is selected in the regions 26 and 28 outside the target region 22 which raises the surface energy of the surface 18 and / or 20 in the regions 26 and 28 outside the target region 22 (gap region 16). The introduced wetting effect, as itself or in combination with the shrinkage characteristics of the adhesive material in case of the bonding process or of the molten material of the optical component 14 in case of the molding process, enhance and accelerate abutting and bonding of the connected surfaces 18, 20 in the regions 26 and 28 outside the gap region 16. Such a wetting treatment in the region or regions outside the target region 22 may lead to a lack of close contact in the target region 22 after the completion of the bonding or molding process when the optical components 12, 14 are successfully connected in the regions outside the target region 22. In other words, the desired gap region 16 is created in the target region 22 after the successful combining of the two optical components into the optical arrangement 10 since their bonding in the one or more regions 26, 28 subject to the wetting treatment has been accelerated.

[0072] Furthermore, the surface treatment and / or the surface treatment parameters can be configured or selected with reference to the shrinkage characteristics of the adhesive material in case of the bonding process or of the material of the optical component 14 in case of the molding process and / or the shrinkage characteristics of the corresponding material can be adjusted with reference to the selected surface treatment and / or surface treatment parameters so as to provide the required gap through a controlled delamination.

[0073] The region or regions 26, 28 subject to the wetting treatment may include the whole area of the surface of the optical component 12 and / or the whole area of the surface 20 of the optical component 14 except for the target region 22 or target regions 22 where the gap region 16 is to be created.

[0074] Fig. 5A and 5B show an embodiment in which the optical arrangement is produced by bonding the optical component 14 to the optical component 12 by using an adhesive 24. Fig. 5A shows a target region 22 in which the gap region 16 is to be created. The target region 22 is a region of the surface 18 of the optical component 12 which is subject to a surface treatment prior to applying the adhesive 24. The surface treatment in the target region 22 is configured or selected so as to enhance a repelling effect of the surface 18 vis-a-vis the adhesive 24. Fig. 5B shows the delamination of the adhesive 24 after solidification (hardening, curing) of the adhesive 24 in the target region 22 so that the air gap region 16 is created in a predefined position and in a controlled manner.

[0075] In the embodiments of Fig. 5A and Fig. 5B, the regions 26, 28 of the surface 18 outside the target region 22 may be subject to a further surface treatment which is configured or selected so as to enhance a wetting effect of the surface 18 in said regions outside the target region 22 as described above.

[0076] Figs. 6A and 6B show an embodiment of the method of producing the optical arrangement 10, in which the optical component 14 and the optical component 12 are bonded to each other by using an adhesive 24. Differently from the embodiment in Figs. 5A and 5B, the surface 20 of the optical component 14 as well as the surface 18 of the optical component are subject to a surface treatment in the target region 22 where the gap region 16 is to be created, which surface treatment enhances a repelling effect of the surfaces 18 and 20 with respect to the adhesive 24 in the target region 22. As described above, this embodiment is advantageous as the repelling effects in the target region 22 are strengthened during the bonding, and a desired height and shape of the resultant gap region 16 may be ensured.

[0077] In the embodiment of Figs. 6A and 6B, it is also possible to subject the regions 26, 28 of the surface 18 and / or the surface 20 outside the target region 22 to a surface treatment which is selected or configured to enhance a wetting effect of the surface 18 and / or the surface 20 vis-a-vis the adhesive 24.

[0078] As mentioned above, all the surface treatments and / or the surface treatment parameters in the embodiments described above may be aligned with the shrinkage characteristics of the adhesive 24 in case of the bonding process or with the shrinkage characteristics of the molten material of the optical component 14 in case of the molding process, and / or the shrinkage characteristics of the adhesive 24 or of the molten material can be adjusted with reference to the selected surface treatment and / or the surface treatment parameters.

[0079] The surface treatments which enhance a wetting effect or enhance a repelling effect, may include a plasma treatment, such as plasma activation, coating, such as thin-film coating, surface grafting, acid etching, and scratching and other mechanical processing of surfaces.

[0080] The described surface treatments may be achieved by or include any other technical means and technological processes for changing or modulating a surface energy in a region of a surface.

[0081] In the following, practical process examples of the bonding process and the molding process including materials and surface treatments to change a surface energy are provided solely with explanatory purposes and thereby said examples do not impose any limitations to the scope of the present invention which is defined by the appended claims.

[0082] For the bonding process, a process example is as follows:- Step 1 : Providing a first optical component made of Polycarbonate.- Step 2: Surface treating a first surface of the first optical component in a pre-defined region or regions where a gap is or gaps are to be created by means of local application of a clean coat by vacuum deposition, for example, in a way as known in the field of eyeglasses / ophthalmic lenses manufacture, in the pre-defined region(s).- Step 3: Applying a UV curable acrylic based optical clear adhesive on the whole area of the first surface of the first optical component to form a continuous layer the adhesive.- Step 4: Stacking a second optical component made of Polycarbonate onto the first surface of the first optical component with the continuous layer of the adhesive.- Step 5: Starting a UV curing process for bonding the first and second optical components to each other with the adhesive.- Step 6: Putting the bonded stack of the first and second optical component into an oven at 120° C for 10 minutes.As a result, a delamination gap occurs within the bonded stack in the clean coat application region(s) either during the UV curing process or after it, e.g. during the temperature treatment in the oven.For the molding process, a process example is as follows:- Step 1 : Providing a first optical component: made of Polycarbonate.- Step 2: Surface treating a first surface of the first optical component in pre-defined region or regions where a gap is or gaps are to be created by means of applying a release agent, for example, one of standard release agents as known and used in the injection molding industry, in the pre-defined region(s).- Step 3: Molding over the first optical component with molten Polycarbonate to form a second optical component on the first surface or around the first optical component.In this example, a delamination gap occurs between the first surface of the first optical component and the second optical component in the release agent application region during solidification of the molten Polycarbonate or after it.

Claims

Claims1. Method of producing an optical arrangement (10) comprising a first optical component (12) having a first surface (18) and a second optical component (14) having a second surface (20) integrally connected to the first surface (18) except for at least one gap region (16) having at least one gap between the first and second surfaces (18, 20), the method comprising: providing the first optical component (12); surface treating the first surface (18) of the first optical component (12) in one or more predefined regions (22, 22a) of the first surface (18) to change a surface energy of the first surface in said one or more predefined regions )22, 22a); providing the second optical component (14) with the second surface (20) integrally connected to the first surface (18) of the first optical component (12) by means of direct contact or through a continuous layer of adhesive (24); and waiting for a pre-defined time for creating the at least one gap region (16) having at least one gap between the first and second surfaces (18, 20) by delamination of a material of the second optical component (14) or the adhesive (24) from the first surface (18).

2. Method of claim 1, wherein the surface treating is configured to enhance a repelling effect on the first surface (18), and the surface treating is performed in at least one first predefined region (22, 22a) of the first surface (18) which corresponds to the at least one gap region (16).

3. Method of claim 1 or 2, wherein the surface treating is configured to enhance a wetting effect on the first surface (18), and the surface treating is performed in atleast one second predefined region (26, 28) which is outside the at least one gap region (16).

4. Method of claim 1 , wherein the surface treating comprises a first surface treating configured to enhance a repelling effect on the first surface (18), and the first surface treating is performed in at least one first predefined region (22, 22a) of the first surface (18) that corresponds to the at least one gap region (16), and the surface treating further comprises a second surface treating configured to enhance a wetting effect on the first surface (18), and the second surface treating is performed in at least one second predefined region (26, 28) outside the at least one gap region (16).

5. Method of claim 3 or 4, wherein the at least one second predefined region (26, 28) includes the whole or substantially the whole area of the first surface (18) except of the at least one gap region (16).

6. Method of claim 1 , wherein the providing of the second optical component (14) comprises bonding the second surface (20) to the first surface (18) using the continuous layer of the adhesive (24), wherein the surface treating is configured to enhance a repelling effect or a wetting effect on the first surface (18) with respect to the adhesive (24).

7. Method of claim 6, wherein the method further comprises, before the bonding, surface treating the second surface (20) of the second optical component (14) in one or more predefined regions (22, 22b) of the second surface (20), wherein the surface treating of the second surface (20) is configured to enhance a repelling effect or a wetting effect on the second surface (20) with respect to the adhesive.

8. Method of claim 6 or 7, further comprising: selecting the surface treatment and / or surface treatment parameters with reference to shrinkage characteristics of the adhesive (24) to enable the delamination of the adhesive (24) in the one or more predefined regions (22, 22a, 22b) during solidification or thermal shrinkage of theadhesive (24), and / or adjusting the shrinkage characteristics of the adhesive (24) with reference to the selected surface treatment and / or the surface treatment parameters.

9. Method of claim 1 , wherein the providing of the second optical component (14) comprises creating the second optical component (14) by molding or casting the second optical component (14) from a molten material or curable material onto at least a part of the first surface (18) of the first optical component (12), wherein the surface treating is configured to enhance a repelling effect or a wetting effect on the first surface (18) with respect to the molten material or curable material of the second optical component (14), and the pre-defined time comprises a time of solidification of the molten material or curable material.

10. Method of claim 9, further comprising: selecting the surface treatment and / or surface treatment parameters with reference to shrinkage characteristics of the molten material or curable material to enable the delamination of the molten material or curable material in the one or more predefined regions (22) during solidification or thermal shrinkage of the molten material or curable material, and / or adjusting the shrinkage characteristics of the molten material or curable material with reference to the selected surface treatment and / or the surface treatment parameters.11 . Method of any one of claims 1 to 10, wherein the surface treating comprises one or more of the following: plasma treating, coating, surface grafting, acid etching, and mechanical surface processing.

12. Method of any one of claims 1 to 11 , wherein the first optical component (12) is one of an optical waveguide and a lens, and the second optical component (14) is another one of the optical waveguide and the lens.

13. Optical arrangement (10) for a head-mounted display, the optical arrangement being produced by a method according to any one of claims 1 to 12.

14. Optical arrangement (10) comprising a first optical component (12) having a first surface (18) and a second optical component (14) having a second surface (20) integrally connected to the first surface (18) except of at least one gap region (16) having at least one gap where a material of the second optical component (14) is delaminated from the first surface (18).

15. Optical arrangement (10) comprising a first optical component (12) having a first surface (18) and a second optical component (14) having a second surface (20) integrally connected to the first surface (18) through a continuous layer of adhesive (24) except of at least one gap region (16) having at least one gap where the adhesive (24) is delaminated from the first surface (18) and / or the second surface (20).

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