Method and screen printing apparatus for coating a light-reflecting layer on a waveguide

Abstract

A method (500) for coating a light-reflecting layer on a waveguide having an intercoupler grating, the method comprising: depositing ink by screen printing (502) on the intercoupler grating of the waveguide.

Description

[Technical Field]

[0001] The embodiments described herein relate to a method for coating a light-reflecting layer on a waveguide having an intercoupler grating and to a screen printing apparatus. The embodiments described herein further relate to a waveguide comprising an intercoupler grating and a lens including an optical waveguide. [Background technology]

[0002] Virtual reality is generally considered to be a computer-generated simulated environment perceived / experienced by a user. The virtual reality experience may be generated in 3D and viewed through a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as lenses to display the virtual reality environment that is experienced in place of the real environment.

[0003] Augmented reality allows a user to still look through the display lenses of glasses or other HMD devices to see the surrounding environment, and also see images of virtual objects that appear to be generated for display and superimposed on the environment. Augmented reality can include any type of input, such as audio and tactile input, as well as virtual imagery, graphics, and video that augment or extend the environment the user experiences. As an emerging technology, augmented reality faces many challenges and design constraints.

[0004] Optical combiners may be used to allow computer-generated virtual images to be combined with real-world images of an environment for the purpose of providing an augmented reality experience. Such optical combiners may involve a waveguide that includes a substrate having a plurality of optical structures formed thereon.

[0005] An optical combiner may require the use of lenses including waveguides, in particular lenses having input and / or output couplers configured such that, for example, light rays of the computer-generated image incident on the input coupler are transmitted through the waveguides to, for example, reach an output coupler, and then the light is ultimately directed towards the eye of a human user, overlapping with light from the physical world passing through the lens.

[0006] The efficiency of the input coupler is important for the efficiency of the optical combiner and / or the quality of the superimposed image. Therefore, there is a need to improve the input coupler and / or waveguides and lenses for augmented reality virtual reality applications. Summary of the Invention

[0007] The invention is defined by the independent claims. The dependent claims define further embodiments of the invention.

[0008] According to one aspect, the present disclosure discloses a method for coating a light reflective layer on a waveguide having an in-coupler grating, the method comprising: - Depositing ink by screen printing onto the waveguide in-coupler grating Includes:

[0009] The present disclosure further discloses a waveguide including an inter-coupler grating having a particle-free light-reflecting layer produced by deposition and sintering of a particle-free ink that adheres to the inter-coupler grating, the light-reflecting layer that adheres to the inter-coupler grating of the waveguide being obtained using the method of the present disclosure.

[0010] The present disclosure further discloses a lens including a light guide of the present disclosure having a length of 40 mm to 80 mm and a width of 20 mm to 60 mm.

[0011] According to a further aspect, the present disclosure provides a method for manufacturing a semiconductor device comprising: - a loading and unloading system for the waveguide; a handling system configured to handle the waveguides loaded by the loading and unloading system; - one or more alignment systems and one or more actuators configured to align and move the waveguides handled by the handling system; - one or more screen printing heads, each including a screen, one or more squeegees, and one or more flood bars configured to apply ink onto a waveguide aligned and moved by one or more alignment systems; A screen printing apparatus comprising: [Brief explanation of the drawings]

[0012] [Figure 1A] FIG. 10 shows a detail of a top view of a lens including a waveguide according to an embodiment of the present disclosure. [Figure 1B] FIG. 10 illustrates a detail of a side view of a waveguide according to an embodiment of the present disclosure. [Figure 1C] 1A-1C illustrate the propagation of light within and / or through a waveguide according to an embodiment of the present disclosure. [Figure 2A] FIG. 1 illustrates a side view of a waveguide having an in-coupler grating including an optically reflective layer according to an embodiment of the present disclosure. [Figure 2B] FIG. 1 shows a side view of a waveguide having an in-coupler grating including an optically reflective layer according to an embodiment of the present disclosure, further illustrating the presence of a protective coating according to an embodiment of the present disclosure. [Figure 2C] FIG. 10 illustrates details of a waveguide in-coupler grating according to an embodiment of the present disclosure. [Figure 2D] FIG. 10 illustrates a detail of a reflective layer on an in-coupler grating of a waveguide according to an embodiment of the present disclosure. [Figure 3A] FIG. 1 illustrates a screen-printed protective mask with a negative-pattern intercoupler grating according to an embodiment of the present disclosure. [Figure 3B]1A and 1B show a screen-printed protective mask with a negative-pattern intercoupler grating according to an embodiment of the present disclosure, further showing a light-reflecting layer on a waveguide with an intercoupler grating according to an embodiment of the present disclosure. [Figure 3C] FIG. 1 illustrates a light reflecting layer on a waveguide having an in-coupler grating according to an embodiment of the present disclosure. [Figure 3D] FIG. 1 illustrates a light reflecting layer on a waveguide having an in-coupler grating according to an embodiment of the present disclosure. [Figure 4A] FIG. 1 illustrates a screen printing apparatus according to an embodiment of the present disclosure. [Figure 4B] FIG. 1 illustrates a screen printing apparatus according to an embodiment of the present disclosure. [Figure 5] 1A-1C illustrate a method for coating a light reflecting layer on a waveguide having an in-coupler grating according to the present disclosure. [Figure 6] FIG. 1 illustrates a waveguide stack including several waveguides according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the following description, the conjunction "or" is not necessarily intended as an exclusive or (xor) unless expressly stated otherwise. Thus, the expressions "or" and "and / or" define the same conjunction, which evaluates specifically to true if both operands are true.

[0014] The embodiments described herein involve optical devices. A device may be considered an optical device if the optical properties of the device are important to the method or instrument in which it is used. At least a portion of the optical device may be made of a transparent material, such as glass or plastic. Some optical devices may be configured to change the properties of light, such as the propagation direction. For example, the optical device may include an optical structure to change the propagation direction of the light. Other optical devices may be unstructured, allowing light to pass through the optical device substantially unchanged. The optical devices described herein may be optical devices for use in augmented reality applications. The optical device may also be referred to as an optical element. An example of an optical device includes a waveguide and a transparent cover element, such as a cover glass, as described herein.

[0015] The optical devices described herein, such as waveguides or transparent cover elements, can be thin pieces of material. The optical devices can be plate elements, including plate elements with flat surfaces or plate elements with curved surfaces. The optical devices can have a first major surface and a second major surface opposite the first major surface. The optical devices can be substantially two-dimensional, and the thickness between the first and second major surfaces of the optical device can be much smaller (e.g., 1% or less) than a dimension, such as the length or width, of the first or second major surface.

[0016] FIG. 1A shows a detailed top view of a lens 100 including a waveguide 10 according to an embodiment of the present disclosure.

[0017] Waveguide 10 may include and / or be formed by substrate 102, which may be a thin piece of transparent material such as glass or plastic. Waveguide 10 may include input coupler grating 104 defined by a grating structure, which may be disposed on substrate 102. Waveguide 10 may include an output coupling region defined by output coupler grating 108, which may be disposed on substrate 102. Light, particularly light corresponding to a virtual computer-generated image, may be coupled into waveguide 10 at the input coupling region defined by in-coupler grating 104. The light may propagate through waveguide 10 until it reaches output coupler grating 108.

[0018] At the output coupler grating 108, light can exit the waveguide 10. Furthermore, the output coupling region formed by the output coupler grating 108 also allows light from the external real-world surroundings to be transmitted through the waveguide 10, thereby allowing a user to see a combination of virtual and real-world images. The waveguide 10 can be a waveguide combiner to provide a user with an augmented reality experience.

[0019] In an augmented reality and / or virtual reality device, an image, usually computer-generated, is transmitted to the eyes of a human user, who perceives the image as superimposed on and / or in place of the physical environment surrounding the user.

[0020] For example, a lens including a waveguide can be used to combine the computer-generated image with the light of the physical environment so that the user effectively sees a superimposition of the physical environment and the computer-generated image.

[0021] A computer-generated image can include any type of data. For example, a computer-generated image can include images recorded at different locations and / or times. For example, a computer-generated image can represent data processed by a computer and / or transmitted over a communication network, by a cloud computing system, over a network, and / or over the Internet.

[0022] Computer generated images can include the transmission of any type of data / information received by the human eye, including data encoded / presented as text and / or numbers.

[0023] The computer-generated imagery may be updated in real time to allow a user to experience a sequence of computer-generated imagery, which may be part of a video that the user may experience, contained in a virtual reality or superimposed with their perception of the surrounding reality.

[0024] Computer-generated images, whether still or included in a video, may be generated through any suitable projector system or lighting system configured to display images and / or video.

[0025] Then, when entering the eyes of a human user located within the physical environment, the image is combined / superimposed with or replaces the light from the physical environment, and the human user's eyes then experience the generated augmented or virtual reality, respectively.

[0026] The coupling may be performed using a lens that includes a waveguide.

[0027] Lens 100 may include additional waveguides, particularly for different wavelengths or ranges of wavelengths. For example, lens 100 may include three waveguides 10, one for each color range of an additive color model, such as the RGB color model.

[0028] The waveguide 10 includes an inter-coupler grating 104 .

[0029] An exit pupil expander 106 may optionally be included in the waveguide 10 .

[0030] The intercoupler grid 104 receives light beams, for example light beams emitted by a projector that projects a computer-generated image or any light-emitting device, for example light beams of color channels, such as RGB color channels.

[0031] The light beam received by the in-coupler grating 104 is then forwarded within the waveguide 10 toward the out-coupler grating 108. The light beam travels as light within the waveguide 10 from the in-coupler grating 104 to the out-coupler grating 108. The waveguide 10 can use an exit pupil expander 106 configuration to create an appropriate eyebox area, so that the out-coupler grating 108 provides an output beam that is perceived by a human user as being focused and sharp. The function of the eye pupil expander is to propagate and expand the size of the light beam to match the output coupler.

[0032] 1B shows a detailed side view of a waveguide according to an embodiment of the present disclosure, particularly showing an in-coupler grating 104 and an out-coupler grating 108 disposed on a substrate 102 of the waveguide 10.

[0033] FIG. 1C illustrates the propagation of light within and / or through waveguide 10 according to an embodiment of the present disclosure.

[0034] Incident light 120 , typically from a projector or light emitting device (not shown), reaches the in-coupler grating 104 of the waveguide 10 of the lens 100 .

[0035] The incident light 120 is then at least partially reflected by the in-coupler grating 104 of the waveguide 10 and propagates within the waveguide 10 and / or the exit pupil expander 106 and / or the substrate 102 as propagating light 122. The propagating light 122 then reaches the out-coupler grating 108, which creates an output light beam 124 that typically reaches a human eye 130 of a human user. Alternatively, an animal's eye or a video camera can replace the human eye 130.

[0036] For augmented reality applications, an additional external light beam 126 originating from the external physical environment 132 can also pass through the interior of the waveguide 10 within the lens 100, resulting in a suitable combination / superimposition of the output light beam 124 and the external light beam 126. In this way, the computer-generated image projected as the incident light 120 is integrally combined with the perception of the physical environment 132, and the user's human eye 130 experiences a visual superimposition of the physical environment 132 and the computer-generated image.

[0037] For virtual reality applications, the external light beam 126 originating from the physical environment 132 may be blocked, so that the user can experience only the computer-generated imagery transmitted by the incident light 120.

[0038] The appropriate configuration of lens 100 including one or more waveguides 10 can produce smooth color and / or 3D visuals for augmented reality and / or virtual reality applications.

[0039] To improve the vision experienced by the user's human eye 130, it is beneficial to maximize the reflection of the incident light 120 at the intercoupler grating 104, thereby maximizing the propagating light 122.

[0040] The present disclosure provides improved in-coupling of incident light 120 into waveguide 10.

[0041] FIG. 2A shows a side view of a waveguide 10 having an in-coupler grating 104 including a light-reflecting layer 202 according to an embodiment of the present disclosure.

[0042] In the present disclosure, the light-reflecting layer 202 is coated on the waveguide 10 having the intercoupler grating 104. According to the method of the present disclosure, an ink is deposited on the intercoupler grating 104 of the waveguide 10 by screen printing. The ink may be a particle-free ink. The ink may be a silver ink. The ink may then be subjected to a treatment, such as a heat treatment or sintering process or UV curing, to obtain the light-reflecting layer 202. The light-reflecting layer 202 can be obtained particularly on the intercoupler grating 104 to improve the reflection of the incident light 120 into the waveguide 10 and thereby improve or maximize the propagating light 122 within the waveguide 10.

[0043] The present disclosure solves the problem of coating a light-reflecting layer onto nanostructures formed by interfacial gratings in air.

[0044] The light reflecting layer 202 improves the in-coupling of the incident light 120 into the waveguide 10, thereby improving the propagating light 122 to obtain an improved image presented to the human eye 130.

[0045] Without the optically reflective layer 202, the first-order diffraction fraction, i.e., the light collected within the waveguide as total internal reflection, is, for example, approximately 10% at the in-coupler, and similarly, the light collected from the waveguide is, for example, approximately 10% at the out-coupler, with an overall efficiency (from input to output) of 1%. Adding the reflective layer 202 at the in-coupler can have an increase of, for example, up to 50%, with an overall coupling efficiency of 5%.

[0046] The present disclosure relates to methods for coating, for example, nanostructures formed by glass, high refractive index surfaces, or a combination of the two, for example, by nanostructured metal oxide coated glass or SiC substrates, for example, onto waveguide in-coupler gratings. In some embodiments, the waveguide 10 consists of or includes a glass substrate or substrate having a refractive index greater than 1.8.

[0047] Embodiments of the present disclosure relate to specialty materials that are optically reflective and adhere to nanostructures on a substrate.

[0048] FIG. 2B shows a side view of a waveguide 10 having an in-coupler grating 104 including an optically reflective layer 202 according to an embodiment of the present disclosure, further illustrating the presence of a protective coating layer 210 according to an embodiment of the present disclosure.

[0049] In some embodiments, the material forming the light-reflecting layer 202 is obtained by ink, in particular particle-free ink, and is deposited by screen printing on top of the lens / waveguide intercoupler grating 104 structure. The light-reflecting layer may then be protected by a resist that prevents oxidation and discoloration.

[0050] The deposition of the ink to obtain the light-reflecting layer 202 may be carried out by an additive process based on silk-screen printing.

[0051] In some embodiments, a protective coating 210 is applied onto the light reflective layer 202, for example, onto the ink after the ink has been treated, for example, with a heat treatment or sintering process or UV curing.

[0052] The problem solved by the present disclosure is to deposit a material that, upon processing, forms an optically reflective layer 202 that functions as an optical mirror in the visible wavelength range. Processing of a substrate is performed to obtain the optically reflective layer 202. The substrate may comprise a waveguide 10 having an inter-coupler grating 104.

[0053] The present disclosure solves the problem of coating nanostructures on a substrate in air using additive or subtractive deposition methods. A pattern is deposited on top of an incoupler grating. The pattern may involve the use of particle-free ink, particularly particle-free Ag ink (silver ink). The pattern forms a light-reflecting layer 202. The pattern / light-reflecting layer 202 is deposited on top of the incoupler grating 104 to increase coupling efficiency due to the high light reflectivity of the processed material.

[0054] Particle-free silver ink can achieve higher reflectivity than deposited aluminum, thereby providing an improved light reflective layer 202 on the waveguide in-coupler grating 104 that improves reflection of the incident light 120, thereby providing better in-coupling to the waveguide 10.

[0055] The present disclosure further overcomes the limitations of deposited aluminum, particularly those associated with masking and sputtering or physical vapor deposition of aluminum, which is expensive and slow.

[0056] The subject matter of the present disclosure may be combined with other processes, for example, to define electrical circuits.

[0057] The light reflecting layer 202 provides an optical mirror obtained, for example, by particle-free ink using screen printing.

[0058] The substrate to be processed, for example the waveguide 10 with the inter-coupler grating 104, may be e.g. a glass substrate with a refractive index (RI) greater than 1.45 (RI>1.45) provided with a planar or nanostructured coating, for example forming the substrate 102 and / or the inter-coupler grating 104; a high refractive index substrate (RI>1.8) with a planar or nanostructured coating, for example forming the substrate 102 and / or the inter-coupler grating 104, or a plastic substrate provided with a planar or nanostructured coating, for example forming the substrate 102 and / or the inter-coupler grating 104; It could be.

[0059] Screen printing is a circular wafer of 150 mm to 300 mm and a thickness of 0.3 mm to 0.8 mm, containing a plurality of waveguides 10, or - A single waveguide / lens (after the wafer has been diced) with typical dimensions of 40-80mm in length and 20-60mm in width may be performed on the

[0060] The materials deposited to form the light-reflecting layer 202 are: - particle-free ink, or - Metal particle ink It could be.

[0061] The wafer may be a glass substrate on which one or more waveguides reside, for example a plurality of waveguides that have not yet been diced / separated.

[0062] FIG. 2C shows details of the in-coupler grating 104 of the waveguide 10 according to an embodiment of the present disclosure.

[0063] For example, the in-coupler grating 104 may be formed by a set of gratings having the shape of sloped fins disposed on the substrate 102, as exemplarily shown in FIG. 2C, and / or any other suitable shape for performing the in-coupling function of the waveguide to the substrate 102.

[0064] The grating shown in FIG. 2C may be the grating structure of the in-coupler grating 104 or the grating structure of the out-coupler grating 108, and thus may serve to provide an input or output coupling region for the waveguide 10. The grating structure may be formed on a major surface of the substrate 102. The grating structure may include multiple optical structures. The optical structures may be configured to change the propagation direction of light incident on the grating structure. The optical structures may have dimensions, e.g., width and / or height, in the sub-micron and even nanometer range. The optical structures may be positioned next to each other with a gap in between. The optical structures may be shaped, for example, as tapered fins.

[0065] 1A-2D, and applies to other waveguides as well. For example, a waveguide can have more than two grating structures (e.g., a waveguide can have one or more intermediate regions defined by additional grating structures), the configuration and shape of the optical structure can differ from the example shown in FIG. 2C, a waveguide can have grating structures disposed on both sides of the waveguide, and so on.

[0066] The waveguide 10 described herein may include a substrate 102. The waveguide may include a plurality of optical structures formed on the substrate. The optical structures may have sub-micron dimensions, e.g., nano-sized dimensions. The plurality of optical structures may form one or more grating structures on the substrate. The waveguide may be a waveguide combiner. The waveguide combiner may be configured to combine a virtual computer-generated image with a real-world image of the surrounding environment. The waveguide may be an augmented reality waveguide combiner.

[0067] In optical systems such as augmented reality devices, several waveguides may be stacked on top of each other to form a waveguide stack. For example, each waveguide in the waveguide stack may be configured to manipulate light in a respective wavelength range, which is useful for providing color images.

[0068] FIG. 2D shows details of the optically reflective layer 202 above the in-coupler grating 104 of the waveguide 10 according to an embodiment of the present disclosure.

[0069] The light reflecting layer 202 is formed on and / or between the angled fins disposed on the substrate 102 of the waveguide 10 , thereby improving the reflection of the incident light 120 .

[0070] The deposition method may be any one or a combination of the following processes: - silkscreen printing with a positive pattern, ink jetting, dispensing, additive processes based on aerosols, to obtain the light-reflecting layer 202 by screen printing; - subtractive processes based on a protective mask with a negatively patterned mirror / incoupling grating combined with silkscreen printing, ink jetting, dispensing, aerosol or spin coating; the protective mask may be a screen-printed protective mask and / or a water-soluble polymer material deposited by ink jetting with a thickness of 2-5 um and a resolution of 10-20 um, or - A combination of the previous methods.

[0071] FIG. 3A shows a screen-printed protective mask 302 having a negative pattern of an intercoupler grating 104 according to an embodiment of the present disclosure.

[0072] FIG. 3B shows a screen-printed protective mask 302 having a negative pattern of inter-coupler grating 104 according to an embodiment of the present disclosure, and further shows a light-reflecting layer 202 on top of the waveguide 10 having inter-coupler grating 104 according to an embodiment of the present disclosure.

[0073] The reflective layer 202 can be obtained by silkscreen printing.

[0074] 3C and 3D show a light-reflecting layer 202 on a waveguide with an inter-coupler grating according to an embodiment of the present disclosure, which can be obtained after removing a screen-printed protective mask 302, or alternatively, after removing a water-soluble polymer material deposited by ink-jetting to form an alternative protective mask.

[0075] The screen alignment method is, for example, - fiducial marks on the wafer or single waveguide, - Edge of wafer (notch) or single waveguide, - patterned nanostructures on a wafer or a single waveguide, or - A combination of the above methods It may be based on.

[0076] The treatments applied to the deposited material include: - application of thermal, conductive, convective, or radiation (photon, laser) heating, or a combination thereof; - UV curing, a two-step process comprising one step for evaporating the solvent present in the deposited material and one step for realizing the optical properties, for example by sintering or curing, or - A combination of the above processes It could be.

[0077] The protective coating layer 210 applied to the material as an encapsulant may be deposited by one of the following methods: - The deposition method of the protective coating can be the same or different from that of the optical material (e.g., silkscreen printing, ink jetting, aerosol, spin coating), - The curing method may be the same as or different from the optical material (thermal or UV), - the coating prevents oxidation and / or corrosion of the optical material, and / or - The coating improves the adhesion and durability of optical materials.

[0078] The printing may be screen printing, for example silk screen printing.

[0079] In the case of silkscreen printing in any of the methods described previously, for example to coat a light reflecting layer on a waveguide with an incoupler and / or for a protective coating, the screen may be - Traditional screens, including wire mesh and flat emulsions, - a stepped screen comprising a wire mesh and two levels of emulsion, the lower thickness of the emulsion serving to reduce the effective force acting on the substrate during the printing process, or - A metal stencil with a stepped thickness, where the metal thickness of the emulsion helps to reduce the effective force acting on the substrate during the printing process. It could be.

[0080] After processing, if the deposited material is conductive, it may be used to create an electrical circuit along the shape of each lens.

[0081] The deposited material may be deposited and processed simultaneously in the mirror area, for example in the in-coupler of the lens, and in other areas of the lens.

[0082] 4A and 4B illustrate a screen printing apparatus 400 according to an embodiment of the present disclosure.

[0083] The screen printing apparatus 400 includes: - a loading and unloading system for the waveguide; a handling system configured to handle the waveguides loaded by the loading and unloading system; - one or more alignment systems 408 and one or more actuators configured to align and move the waveguides handled by the handling system; one or more screen printing heads 402, each including a screen 406, one or more squeegees 404, and / or one or more flood bars configured to apply ink onto a waveguide that is aligned and moved by one or more alignment systems; Includes:

[0084] The screen printing apparatus, and in particular the loading and unloading system of the screen printing apparatus, can handle waveguides in glass wafers, for example, approximately 20 waveguides in a 300 mm wafer, or separate, already cut waveguides that can be placed in a specific printing chuck with precise alignment and multiple printing processes, or alternatively, separated and printed one by one.

[0085] In some embodiments, the waveguide is a single waveguide, or multiple waveguides in a glass wafer, or multiple, separate and already cut waveguides placed in a printing chuck.

[0086] A single screen may be used to screen print on multiple waveguides in a glass wafer or separated and placed in a print chuck. A conveyor system 410 can transport wafers / lenses / waveguides to and / or from the handling system for processing. The wafers / lenses / waveguides forming the substrate to be processed can be moved in a movement direction 420 that can be substantially parallel to the screen 406.

[0087] More specifically, for screen printing applications, the equipment may be, for example: - Manual or automatic loading and unloading systems for wafers, single waveguides / lenses, or trays of waveguides / lenses; one or more alignment systems 408 based on optical cameras, dedicated illumination systems, and groups of actuators in X, Y, and angular directions, where the alignment systems can detect either the substrate edge, the fiducials, or the patterned nanostructures, and the actuators move either the substrate, the printing screen, or both; - one or more screen printing heads 402 made up of a screen 406, one or more squeegees 404, and one or more flood bars; - Optional air filtering system (FFU) for cleanroom grade 1,000 and above, - an optional processing station that can be integrated into the printing module (thermal or UV), - a handling system (i.e., rotary table, linear shuttle, ...) for carrying the wafer / lens on the processing station and holding the wafer / lens during the process (i.e., printing), and / or - a conveyor system 410 for transporting wafers / lenses to and / or from the handling system for processing; It may be made of.

[0088] The screen printing apparatus 400 can handle one or more waveguides in parallel. For example, while Figure 4A shows the screen printing apparatus 400 including one print head 402, the screen printing apparatus 400 shown alternatively in Figure 4B includes, among other things, two print heads 402, thereby enabling parallel printing on a substrate.

[0089] Other embodiments can include one, two, or more print heads 402 and / or different numbers and arrangements of components for printing on multiple substrates in parallel.

[0090] FIG. 5 illustrates a method 500 for coating a light-reflecting layer 202 on a waveguide 10 having an in-coupler grating 104 according to the present disclosure.

[0091] The method 500 for coating a light-reflecting layer 202 on a waveguide 10 having an intercoupler grating 104 includes: depositing 502 ink by screen printing onto the in-coupler grating 104 of the waveguide 10; Includes:

[0092] 6 shows a waveguide stack 600 including several waveguides according to the present disclosure. The waveguide stack 600 may be included in the lens 100, for example.

[0093] The waveguide stack 600 may include a cover glass 602a (e.g., a bottom cover glass), a waveguide 10a, a waveguide 10b, a waveguide 10c, and a cover glass 602b (a top cover glass), stacked in this order. An adhesive 604a may be disposed between the cover glass 602a and the waveguide 10a. Adhesives 604b, 604c, and 604d may be disposed between the waveguides 10a and 10b, between the waveguides 10b and 10c, and between the waveguide 10c and the cover glass 602b, respectively. Each of the waveguides 10a-c may be a waveguide described herein, such as the waveguide 10.

[0094] A cover glass, such as a cover slip, may be a protective glass. The cover glass may shield the surface of the waveguide adjacent to the cover glass, for example, to prevent contact or contamination of a grating formed on said surface. The cover glass itself may not have an optical structure, such as a grating.

[0095] The adhesives, such as adhesives 604a-d, may be configured to attach adjacent optical devices of the waveguide stack to one another. For example, adhesive 604a may be configured to attach cover glass 602a to waveguide 10a. The adhesive may be a pressure-sensitive adhesive (PSA). The adhesive may be a preformed adhesive, such as a preformed PSA. The adhesive may have an elongated shape. For example, the adhesive may be an adhesive tape. The adhesive may function as a spacer that provides a gap, in particular an air gap, between adjacent optical devices of the waveguide stack. Thanks to the adhesive, the adjacent optical devices may not contact each other.

[0096] The waveguide stack 600 shown in FIG. 6 includes a total of three waveguides. The present disclosure is not limited thereto. The waveguide stack may include one or more, two or more, or three or more waveguides. For example, the waveguide stack may include a total of two waveguides stacked between cover glass 602a and cover glass 602b.

[0097] Additionally, instead of a cover glass, a transparent cover element made of a material other than glass may be used in the waveguide stack. Throughout this disclosure, a cover glass may be replaced by a transparent cover element.

[0098] In some embodiments of the method 500, the ink may be a particle-free ink. The ink, and / or the ink after application of a treatment to the ink, forms the light reflective layer 202.

[0099] The following briefly summarizes relevant embodiments of the present disclosure.

[0100] In some embodiments of the method 500, the ink is a particle-free ink. In some embodiments, the particle-free ink can be a silver ink.

[0101] In some embodiments, the waveguide 10 comprises a glass substrate or substrates having a refractive index greater than 1.8.

[0102] In some embodiments, the waveguide may be contained in a lens having a length of 40 mm to 80 mm and a width of 20 mm to 60 mm. For example, screen printing may be performed using a single screen on a single lens, on multiple single lenses, or on a substrate where the lenses are present but not yet separated.

[0103] In some embodiments, screen printing is performed using a single screen on a single waveguide, on multiple diced waveguides, or on a wafer / glass substrate where waveguides are present but not yet diced.

[0104] In some embodiments, the ink deposition is performed by an additive process based on silk screen printing.

[0105] The additive process creates a light-reflecting layer 202 on the in-coupler grating 104 of the waveguide 10 .

[0106] In some embodiments, the ink deposition is performed by a subtractive process based on a screen-printed protective mask 302 with a negative pattern of the intercoupler grating 104 combined with silk-screen printing.

[0107] In some embodiments, the method 500 further includes subjecting the ink to a treatment, where the treatment is a heat treatment or sintering process or UV curing, and applying a protective coating 210 to the treated ink.

[0108] The present disclosure further discloses a waveguide 10 comprising an inter-coupler grating 104 having a particle-free light-reflecting layer 202 produced by deposition and sintering of a particle-free ink that adheres to the inter-coupler grating, the light-reflecting layer 202 adhering to the inter-coupler grating of the waveguide being obtained by the method of the present disclosure.

[0109] The particle-free ink is a particle-free ink that forms the light reflective layer 202 according to the present disclosure.

[0110] The present disclosure further discloses a lens including a light guide 10 according to the present disclosure and having a length of 40 mm to 80 mm and a width of 20 mm to 60 mm.

[0111] The present disclosure provides: - a loading and unloading system for the waveguide; a handling system configured to handle the waveguides loaded by the loading and unloading system; - one or more alignment systems 408 and one or more actuators configured to align and move the waveguides handled by the handling system; one or more screen printing heads 402, each including a screen 406, one or more squeegees 404, and one or more flood bars configured to apply ink to a substrate aligned and moved by one or more alignment systems; Further disclosed is a screen printing apparatus 400 comprising:

[0112] A conveyor system 410 can transport wafers / lenses / waveguides to and / or from the handling system for processing / printing.

[0113] In some embodiments, the ink is a particle-free ink and a silver ink.

[0114] In some embodiments, the screen printing apparatus further comprises an air filtering system for a class 1000 or higher clean room.

[0115] Screen printing of particle-free inks according to the present disclosure achieves higher throughput and lower cost, and provides improved reflectivity and improved in-coupling of the waveguide 10.

[0116] In particular, the disclosed method provides an improved coating of an improved light-reflecting layer 202 on a waveguide 10 having an incoupler grating 104. Deposition by screen printing allows for high throughput and low cost compared to waveguides not including such a coating, thereby improving the method for coating a light-reflecting layer on a waveguide having an incoupler grating.

[0117] For example, in typical printing processes and configurations, screen printing and, for example, print-on-print, may require, for example, a range of 2 to 5 seconds per printing step. By comparison, a typical ink jetting head with one nozzle would require, for example, approximately 20 to 30 minutes to produce the same pattern. Even if a high number of nozzles were used in parallel, the screen printing time would be at least comparable and / or still advantageous.

[0118] Although there is significant diffusion on the grating structure due to the lower viscosity of the inkjet ink, which can be several orders of magnitude, a significantly improved pattern fidelity can be achieved by thickening the material. Thus, this application typically achieves significantly improved pattern fidelity and / or improves the time required to create the pattern.

[0119] The particle-free ink, particularly the silver ink, improves the light-reflecting layer 202 on the waveguide 10 having the intercoupler grating 104, thereby providing better reflectivity that improves the light coupled into the waveguide 10 and / or the propagating light 122, thereby achieving an improved intercoupler.

[0120] The screen-printed ink deposition 502 further results in an improved and more uniform light-reflecting layer 202, thereby further contributing to improved reflectivity of the in-coupler and further improving in-coupling of incident light 120 into the waveguide 10 and / or the waveguide 10 into the substrate 102.

[0121] Screen printing improves processing times: for example, where an inkjet system can produce a particular pattern in minutes, screen printing typically produces the same pattern in seconds.

[0122] The patterning ability of screen printing and / or the quality of the resulting light-reflecting layer is usually improved because the paste / ink has a higher viscosity and therefore stays in place better than when using inkjet methods. The patterning ability and / or quality of the resulting reflective layer is evaluated, for example, by considering the placement precision and accuracy in reproducing the pattern / light-reflecting layer.

[0123] Additionally, adhesion of the ink to the substrate and / or interlayer grating is improved when screen printing is used as a result of the application of pressure during paste / ink transfer during screen printing.

Claims

1. 1. A method for coating a light-reflecting layer on a waveguide having an inter-coupler grating, comprising: depositing ink by screen printing onto the incoupler grating of the waveguide; A method comprising:

2. The method of claim 1 , wherein the ink is a particle-free ink.

3. The method of claim 2 , wherein the particle-free ink is a silver ink.

4. 4. The method of claim 1, wherein the waveguide comprises a glass substrate or a substrate having a refractive index greater than 1.

8.

5. 5. The method of claim 1, wherein the waveguide is comprised in a lens having a length of 40 mm to 80 mm and a width of 20 mm to 60 mm.

6. 6. The method of claim 1, wherein the screen printing is performed using a single screen on a single waveguide, on multiple diced waveguides, or on a glass substrate with waveguides present but not yet diced.

7. The method of claim 1 , wherein the deposition of the ink is carried out by an additive process based on silkscreen printing.

8. 7. The method according to claim 1, wherein the deposition of the ink is carried out by a subtractive process based on a screen-printed protective mask having a negative pattern of the intercoupling grating combined with silk-screen printing.

9. 9. The method of claim 1, further comprising subjecting the ink to a treatment, the treatment being a heat treatment or sintering process or UV curing, and applying a protective coating to the treated ink.

10. 10. A waveguide comprising an inter-coupler grating having a particle-free light-reflecting layer, the particle-free light-reflecting layer being produced by deposition and sintering of a particle-free ink that adheres to the inter-coupler grating, the light-reflecting layer adhering to the inter-coupler grating of the waveguide being obtained by the method of any one of claims 1 to 9.

11. 11. A lens comprising the optical waveguide of claim 10 having a length of 40 mm to 80 mm and a width of 20 mm to 60 mm.

12. a loading and unloading system for the waveguide; a handling system configured to handle the waveguides loaded by said loading and unloading system; one or more alignment systems and one or more actuators configured to align and move the waveguides handled by said handling system; one or more screen printing heads, each including a screen, one or more squeegees, and one or more flood bars configured to apply ink onto the waveguides aligned and moved by said one or more alignment systems; A screen printing apparatus comprising:

13. The screen printing apparatus of claim 12 , wherein the ink comprises a particle-free ink and a silver ink.

14. 14. The screen printing apparatus according to claim 12 or 13, wherein the waveguide is a plurality of waveguides in a glass wafer, a plurality of separated and already cut waveguides arranged in a printing chuck, or a single waveguide.

15. The screen printing apparatus according to any one of claims 12 to 14, further comprising an air filtering system for a class 1000 or higher clean room.

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