Method for replicating a plurality of holograms by means of a typecase principle

Abstract

The invention relates to a method comprising: Providing a multiplicity of master elements comprising a substrate body and at least one master hologram, selecting a sequence of master elements from the multiplicity of master elements in dependence on the plurality of holograms to be replicated and arranging the sequence of master elements on a first carrier means such that upper surfaces of the master elements are aligned in a horizontal plane, detachably laminating a light-sensitive composite sheet onto the aligned surfaces of the master elements, exposing the master elements in order to replicate the master holograms in the light-sensitive composite sheet, and detaching the exposed composite sheet from the master elements, wherein the master elements are detachably incorporated in the first carrier means such that a sequence and / or composition of the master elements for the replication of the plurality of holograms is variable and wherein the master elements are incorporated in the first carrier means in such a way that two or more surfaces of the master elements are optically accessible for the purpose of exposure.

Description

[0001] METHOD FOR REPLICATION OF A PLURALITY OF HOLOGRAMS USING A TYPE-CASE PRINCIPLE

[0002] DESCRIPTION

[0003] The invention relates to a method comprising: providing a plurality of master elements comprising a substrate body and at least one master hologram, selecting a sequence of master elements from the plurality of master elements depending on the plurality of holograms to be replicated and arranging the sequence of master elements on a first carrier means such that upper surfaces of the master elements are aligned in a horizontal plane, releasably laminating a photosensitive composite web onto the aligned surfaces of the master elements, exposing the master elements to replicate the master holograms in the photosensitive composite web, and detaching the exposed composite web from the master elements, wherein the master elements are releasably incorporated in the first carrier means,such that a sequence and / or composition of the master elements for the replication of the plurality of holograms is variable and wherein the master elements are incorporated in the first carrier means such that two or more surfaces of the master elements are optically accessible for the purpose of exposure.

[0004] Background and state of the art

[0005] The invention relates to the field of hologram replication.

[0006] HOEs (Holographic Optical Elements) typically refer to optical components in which holographic properties are used to achieve a specific light beam path, such as transmission, reflection, diffraction, scattering, and / or deflection, etc. This allows desired optical functionalities to be implemented compactly in any substrate. The holographic properties preferably exploit the wave nature of light, particularly coherence and interference effects. Both the intensity and phase of the light are taken into account.

[0007] Such holographic elements find application in many areas, such as transparent displays (e.g., in shop windows, refrigerated cabinets, vehicle windows), for lighting applications such as information or warning signals in glass surfaces, and light-sensitive detection systems, for example, for interior monitoring (eye tracking in vehicles or presence status tracking of people indoors). Many HOEs have large dimensions, covering, for example, an entire windshield. On the other hand, HOEs can also have smaller dimensions, for example, for use in banknotes and security seals. Holograms are created by the interference of a reference beam with the light reflected from the surface of an object (object rays). Traditionally, three-dimensional objects have been used to create unique, customized holograms.Today, it is possible to create such holograms using purely computer-generated methods, in which a holographic interference pattern is digitally calculated and "printed" onto a light-sensitive material by computer-controlled coherent light sources. This enables the production of holograms from a computer-generated image and is considered particularly suitable for the production of unique versions of holograms, customized holograms, or for the production of master holograms that are later duplicated. An example of this type of process is known as "laser scanning holography lithography." This process requires the use of very fine laser beams with a beam width in the micrometer range. The process is therefore time-consuming and costly, making its use uneconomical, especially for very large master holograms.

[0008] Commercially available HOEs, on the other hand, are often mass-produced using duplication processes. Such duplication processes typically use a master hologram containing the image to be copied. The master hologram often has similar dimensions to the HOE. The materials for the master hologram are often more expensive than the replicated HOEs, as master holograms are typically made of a more durable metal or embedded in a transparent substrate with higher rigidity and surface quality than a master element. The production of master holograms is also costly due to the use of custom processes, whether traditional or computer-generated.

[0009] Master holograms are often stored in a substrate body that carries the master hologram. The substrate body is preferably transparent. The substrate body preferably has multiple surfaces, including an upper or lower surface that can be horizontally oriented. The combination of the master hologram with the substrate body forms a master element. The size of the master element is typically several times the size of the master hologram. The heavy weight of master elements is caused by the hard, transparent materials used for the substrate body, such as glass.

[0010] The continuous duplication of a single master hologram to produce a series of identical copies of such HOEs is well known. Typically, this process is accomplished by embossing a photosensitive material into a reflection hologram. Duplication can also be accomplished by optical exposure to create a volume hologram. In these cases, a photosensitive material is brought into optical contact with a master element and exposed to coherent light. To enable continuous processing and increase process speed, the photosensitive material can be provided in web form and transported by rollers through various workstations to produce the HOEs. Such webs are often available only in standard widths, which are adapted, for example, to the width of reels in the workstations.

[0011] Especially for small HOEs (width or length <150 mm), their replication on such a web with a single master element often cannot be performed in a process- or material-efficient manner. Especially in cases where the web width exceeds the HOE width by several times, a large portion of the photosensitive web must be cut away and disposed of in subsequent processing steps. This leads to material waste, higher costs, and also limits the speed and efficiency of the copying process.

[0012] An alternative may be the use of multiple master holograms to produce the HOEs side by side across the width of the web. While this improves material utilization, it introduces challenges for master hologram placement. In particular, unevenness between the master holograms can lead to poor optical contact between the web and the master holograms, resulting in unwanted reflections at the interfaces. One possible solution to this problem is to integrate various master holograms into a single, large-area master element. A large-area master element can provide a perfectly flat and continuous surface to establish the required optical contact with the web.

[0013] However, the production of large master elements with numerous master holograms is expensive, partly because the production of large-area, optically flawless polished substrates is not trivial. Furthermore, such master elements are difficult to move due to their weight, making it difficult to insert and remove such large master elements from a production line. Furthermore, the storage and logistical maintenance of a large number of heavy and cost-intensive master elements impractical.

[0014] Furthermore, space-efficient positioning of master holograms can lead to unwanted optical disturbances in the generated HOE. For example, reference beams used to expose a master hologram can spread or be scattered and reach a neighboring hologram, causing it to be accidentally exposed as well. To avoid this, large buffer distances between the master holograms are required, which has a detrimental impact on the material-efficient use of both the master elements and the light-sensitive path. Identical master holograms can be present on a master element to create more efficient use of a light-sensitive path, as explained above. In such a case, one and the same scanning laser can expose all master holograms from the same angle.

[0015] However, it may also be preferable to replicate master holograms of different motifs simultaneously. This may be preferable to use a replication system for different applications simultaneously. It may also be necessary to replicate a large number of HOEs of different types to create a large-area HOE, which are then combined to form a single large-area HOE.

[0016] The various holograms to be replicated can differ from one another not only in the motifs they contain, but also in their type. For example, transmission and reflection holograms are known, which in turn are divided into categories such as edge-lit, back-lit, etc. Holograms for different purposes must be exposed in different ways and from different angles, for example, to match the position of a light source used to reconstruct the hologram. To reduce the effort, it would also be advantageous if different types of master holograms with different motifs and different exposure methods could be exposed on a single track in a single device.

[0017] In the case where the same master element contains a multitude of master holograms of different motifs and types, simple laser scanning across the entire master element is not suitable. Designing an optical setup to expose different master holograms of the same master element from different angles without incorrectly exposing certain areas is complex. Furthermore, in this case, the master holograms in the master element must be separated from each other to avoid unwanted overlap of light rays.

[0018] A further problem arises if one or more master holograms in the master element prove to be faulty, degraded, or need to be modified. Since the master holograms are firmly bonded to the substrate body, they cannot be replaced individually without replacing the entire master element.

[0019] Particularly when changes are only required in a partial area of ​​a larger master hologram, this leads to a large loss of material and increased manufacturing costs. If changes occur frequently and only small series are produced, the process becomes impractical. An alternative is to produce each hologram using a computer-controlled lithography technique. As explained above, however, this is uneconomical for most commercial applications. There is therefore a need to provide a more efficient process for duplicating holograms that allows changes to be made easily and is particularly suitable for the more flexible, material-saving replication of holograms in small and large dimensions. Furthermore, it would be desirable to create simple ways to vary master holograms between short series, with the master holograms being easy to store and exchange.

[0020] For many applications, e.g., for the production of personalized security features (e.g., a holographic date of birth, a holographic issue date, a holographic serial number, or similar), known methods of serial duplication are not readily suitable. This is because the hologram to be produced can either be unique or contain a unique combination of features such as numbers, symbols, and images. Furthermore, these holograms may require different types with different exposure requirements. For example, transmission holograms may be necessary for use in glasses with a specific tint or strength (cf. WO2016202595A1). Likewise, reflection holograms may be required, for example, for use in a display.The holograms may need to be a specific color or only visible from a certain angle.

[0021] US2007024939A1 discloses a method that increases the flexibility of using master holograms in a production run. The method involves bringing a light-sensitive web into contact with a matrix of small, separate master elements. The master elements themselves include variable features such as a counter and are arranged in a frame such that only their upper side is accessible for exposure. The arrangement thus allows exposure from only one side to produce exclusively reflection holograms.

[0022] Furthermore, the arrangement known from US2007024939A1 does not provide for precise guidance of the exposure light to the master elements or the light-sensitive path. The angles from which the light passing through the light-sensitive path can reach the master elements are limited, as the light can only fall on the upper side of the master elements. Therefore, all master elements must be exposed using essentially the same technique. This means that although different master elements (or "objects") can be copied in a single production run, they must all be copied in the same way to produce exclusively reflection holograms. For this purpose, the master holograms are placed against a mirrored background. Furthermore, there is no provision for protecting adjacent copies from interference caused by light reflected from adjacent master holograms.Top-down exposure of the master holograms is revealed to be the only way to create different holograms in the light-sensitive path without unwanted overlaps between the different images. During exposure as described in this document, the reference beam must pass through various components with different optical indices, which cause it to be refracted differently. Interfaces occur between layers with different optical indices—for example, between the master elements, the light-sensitive path, and the surrounding air—where there is a high risk of reflections. This can result in unwanted exposure patterns.

[0023] DE 10 2010 2014 3015 A1 discloses a method for replicating multiple reflection holograms. The holograms to be copied are placed side by side on the surface of a drum with a polygonal cross-section or prismatic shape, with each surface of the drum having at least one master hologram. A light-sensitive material is guided over the surface of the drum for exposure. To eliminate air gaps, particularly at the corners of the drum, between the light-sensitive material and the drum, rollers are guided over the surface of the drum. Similar to the device according to US2007024939A1, this arrangement only allows exposure of reflection holograms. Greater flexibility in exposing different types of holograms is not provided.Furthermore, wrapping the photosensitive material over the surface of a multi-sided prismatic drum can compromise the mechanical quality of the photosensitive material, leaving unwanted creases or wrinkles. Therefore, an arrangement that allows for gentle handling of a composite web is required to perform a flexible replication process.

[0024] In light of the known state of the art, there is therefore a need for a method which not only enables the duplication of different master elements with different master holograms in a single series, but also preferably enables a controlled exposure of each master element from a specific direction or with a specific wavelength, so that different exposure methods can also be carried out in a single series.

[0025] Object of the invention

[0026] The object of the invention is to provide a method for replicating a plurality of holograms without the disadvantages of the prior art. In particular, it was an object of the invention to provide a method suitable for the material-saving replication of holograms with high precision and quality, wherein preferably different holograms with different exposure requirements can also be replicated.

[0027] Summary of the invention

[0028] The object is achieved by the features of the independent claim. Advantageous embodiments of the invention are described in the dependent claims.

[0029] The invention relates to a method for replicating a plurality of holograms, comprising the following steps: a. providing a plurality of master elements comprising a substrate body and at least one master hologram, b. selecting a sequence of master elements from the plurality of master elements depending on the plurality of holograms to be replicated and arranging the sequence of master elements on a first carrier means such that upper surfaces of the master elements are aligned in a horizontal plane, c. releasably laminating a photosensitive composite web onto the aligned surfaces of the master elements, d. exposing the master elements to replicate the master holograms in the photosensitive composite web, and e.Detaching the exposed composite web from the master elements, wherein the master elements are releasably incorporated in the first carrier means such that a sequence and / or composition of the master elements for the replication of the plurality of holograms can be varied and wherein the master elements are incorporated in the first carrier means such that two or more surfaces of the master elements are optically accessible for the purpose of exposure.

[0030] The method according to the invention has the advantage that several master holograms can be exposed in a single series and at the same time offers great flexibility in the exposure method. By providing a large number of master elements and arranging them, for example in a linear arrangement, a large hologram can be formed from several smaller motifs. These can be part of a larger image or appear as an independent component. Additionally or alternatively, the master elements can represent individual holograms that are to be separated after copying. By using several smaller master elements to cover an area normally covered by a single large master element, the complexity of a system can be reduced. Minor changes or defects to a master element do not require the replacement of all elements.In addition, the master elements can be made smaller. This significantly reduces the costs of manufacturing and inserting the master elements. For example, the transparent substrates used to house the master holograms can be prepared and polished more easily. This also offers advantages in terms of the quality of the master elements, as polishing machines often have maximum size limits for the materials used. By limiting the dimensions of the master element, a high degree of polishing can be ensured using simple means. The transport and storage of smaller and lighter master elements is also more economical, as they can be stacked to save space, transported without special lifting devices, and easily inserted into or removed from a replication device.

[0031] Furthermore, the method according to the invention allows for optimal material utilization of the light-sensitive composite web. The carrier can preferably extend across the entire width of the composite web, so that the master holograms can be replicated in areas of the composite web across its entire width. The provision of separate master elements in a carrier advantageously also allows the individual master elements to be optically separated from one another to avoid stray light during the exposure process. For this purpose, for example, side surfaces of the master elements can be provided with a light-absorbing layer. Likewise, the carrier itself can provide light-absorbing spacers. The provision of separate master elements thus allows a number of measures to enable significantly denser positioning of master holograms without compromising the precision or quality of the replication.

[0032] Furthermore, by providing a large number of such master elements, a pool of different building blocks can be created. By selecting master elements from such a large number, a diverse spectrum of different combinations of building blocks can be reproduced on a single light-sensitive material. This offers enormous flexibility in combining building blocks to create a wide variety of images, patterns, or texts, while significantly reducing costs compared to digitally controlled individual holography. Figuratively speaking, individual holography can be compared to handwriting, while selecting master elements from the multitude of master elements utilizes a more economical typecase principle analogous to a Gutenburg press.By selecting the master elements from the multitude of master elements according to a sequence, individual holograms can be produced only in the number and sequence desired by the end user. This is particularly useful in industries that use sequential parts delivery (SPD) or a just-in-sequence (JIS) delivery method of parts, and advantageously enables the integration of the inventive method in such factories. For example, in the automotive industry, which is moving more towards customization and integrating more HOEs in the design of automobiles, the replicated holograms can be delivered in a sequence that harmonizes with the automotive production sequence. This eliminates intermediate logistical steps, increasing efficiency. Since only the exact number required is produced, less waste is also generated.For similar reasons, the method according to the invention is also suitable for high-security applications such as banknotes and identity documents.

[0033] Furthermore, the carrier means advantageously allows the individual master elements to be placed in the device such that they are at fixed, known distances from one another. This ensures very high precision in placement, which allows for the separation of the replicated holograms as needed during the further course of the process. In a preferred embodiment of the invention, the master elements are arranged in a linear arrangement in the first carrier means.

[0034] The support also allows the master elements to be positioned so precisely that their surfaces are flush with each other and with the support. This allows the multiple master elements to be used even with thin, flexible, light-sensitive materials without damaging them. This represents a departure from previous views that the use of multiple master elements arranged side by side in a single pass would result in edges or protrusions on a flowing composite web of light-sensitive material, causing wear or damage.

[0035] Due to the aligned horizontal surface created by combining the master elements with the support medium, a light-sensitive material can instead be laminated to the master elements with high precision and with only low shear forces.

[0036] Lamination brings the light-sensitive material into mechanical contact with the master elements and ensures sufficient optical contact with the master holograms. By laminating the light-sensitive material instead of simply placing it on top of the master elements, a particularly homogeneous contact can be achieved between the master element and the light-sensitive material, effectively preventing bubbles or wrinkles. By using a composite web made of the light-sensitive material, this can be done repeatedly and efficiently across the array of master elements, allowing the composite web to flow while the array of master elements preferably remains stationary. In particular, removable lamination allows the composite web to be removed without damage or residue and passed on to further stations in a production line.

[0037] By constructing the support means such that at least two surfaces of each master element are kept optically accessible, one and the same pass of the process can comprise the exposure of both reflection and transmission holograms. For example, a first master element can be exposed from above on its upper horizontal surface so that the light passes through the photosensitive composite web, is reflected by the master hologram, and passes again through the photosensitive composite web. This would produce a reflection hologram. A second master element can be exposed from the side or from below so that the light passes through the master hologram and then through the photosensitive composite web, producing a transmission hologram. The process thus allows greater flexibility in producing different holograms with different properties in one and the same pass.

[0038] A "sequence" within the meaning of the invention is preferably an order of several elements. The elements in the sequence can be identical and can be repeated or varied. The order is preferably predetermined.

[0039] An "arrangement" within the meaning of the invention is preferably a physical positioning of elements in predetermined positions, preferably according to a predetermined sequence. The arrangement of the master elements is preferably a linear arrangement.

[0040] A "linear arrangement" within the meaning of the invention is preferably a physical positioning of elements such that they form a line along one of their edges, along their center point, and / or another reference point. The "linear arrangement" can preferably comprise multiple lines, forming, for example, rows and columns.

[0041] A "support means" within the meaning of the invention is preferably a means that holds multiple elements in such a way that their positions relative to one another are fixed. Preferably, the support means comprises a frame, a skeleton, and / or a plurality of clamps, wherein the clamps may be referenced to a common mechanical reference, such as a rail. Preferably, the support means comprises gaps and / or recesses designed to precisely fit a master element.

[0042] A "lamination" or "lamination" within the meaning of the invention is preferably a joining process between two components. The lamination is preferably designed such that the composite web continuously covers a surface, so that no gaps, bubbles, or wrinkles are present. The lamination is preferably carried out using a laminating roller. The lamination is preferably carried out at room temperature, for example at a temperature of 20°C - 25°C. However, the laminating roller can also optionally be heated to 20 - 300 °C, preferably 20 - 100 °C or 40 - 80 °C. The temperature of the laminating roller should preferably be set such that the composite web is softened but not melted. The lamination is preferably designed such that no permanent bond is created between the composite web and the master elements or the carrier material.Lamination can also be achieved with the aid of aids such as an adhesive, wherein the adhesive is preferably weak enough that the parts can be separated from each other with a force of less than 10 N, preferably less than 5 N. The adhesive is preferably easy to clean, e.g., due to its water solubility, and leaves no residue on the composite web. Even more preferably, the adhesive evaporates residue-free at room temperature.

[0043] A "composite" within the meaning of the invention is preferably a multilayer material consisting of two or more different components with different physical properties that are bonded together at an interface. Preferably, the bond between the individual components is such that it cannot be severed by the application of slight force and is therefore considered permanent. The composite can consist, for example, of a light-sensitive liquid, a solid, or a resin enclosed between two transparent carrier films. Alternatively or additionally, the composite web can comprise a stack of layers, each light-sensitive to different spectral ranges.

[0044] A “composite web” within the meaning of the invention is preferably a composite material with a length that is at least twice, preferably at least five times, and even more preferably at least twenty times its width. The thickness of the composite web is preferably adjusted so that it has a certain flexibility so that it can, for example, be partially wound around a roller. The composite web preferably has a thickness of up to 300 μm. The composite web comprises a photosensitive material. The composite web preferably encloses the photosensitive material between two transparent support films that have a similar refractive index to the photosensitive material. The refractive index of the support films and the photosensitive material is preferably between 1.4 and 1.6. The photosensitive material can, for example, be a photosensitive photopolymer or a dichroic gelatin.The light-sensitive material can be light-sensitive to the entire visible spectrum or wavelength-selective.

[0045] In the context of the invention, "exposure" is preferably understood to mean the targeted directing of electromagnetic radiation onto a correspondingly sensitive surface, preferably to form a hologram. Various methods for exposing a hologram are known, including transmissive or reflective techniques for producing volume holograms. Examples of these will be explained in more detail later in this text.

[0046] A "master element" is preferably a three-dimensional unit comprising a master hologram in a shape that facilitates its handling and mobility. The master hologram is, in particular, fixedly positioned within the master element such that a movement of the master element directly leads to a corresponding movement of the master hologram. The master element preferably has a length and width approximately corresponding to that of the master hologram. The master element is preferably at least twice, preferably five times, and particularly preferably at least twenty times as high as the master hologram. The master element preferably has a regular shape that allows for a mosaic-like or linear arrangement.

[0047] The master element comprises a substrate body that either encloses or supports the master hologram. In embodiments, the master element may, for example, comprise a transparent top cover for protecting a master hologram located between the cover and the substrate body. Preferably, the top cover has a refractive index selected to allow light to pass through it, the master hologram, and the substrate body without being significantly reflected at the interfaces between the substrate body, master hologram, or cover. The top cover may, for example, be a transparent film or a glass layer. Preferably, the materials of the substrate body, the master hologram, and the cover are selected to minimize the differences in refractive index between the individual layers. This allows internal reflections to be avoided.

[0048] Preferably, the "width" refers to a dimension in a horizontal plane transverse to a composite web flow direction. Preferably, the "length" refers to a dimension in a horizontal plane longitudinal to a composite web flow direction. Preferably, the "height" refers to a dimension in a vertical plane orthogonal to the plane formed by the width and length.

[0049] A "substrate body" within the meaning of the invention is preferably a three-dimensional block of material that carries or encloses the master hologram. The substrate body is preferably transparent. The substrate body preferably has several surfaces, including an upper surface that may be horizontally oriented.

[0050] For the purposes of the invention, the term "transparent" or "transparency" preferably refers to a property of a material whereby it is essentially permeable to light. A transparent material within the meaning of the invention is preferably transmissive for at least part of the electromagnetic spectrum, preferably with a wavelength between 100 nm and 1 mm, particularly preferably between 400 nm and 780 nm. A transparent material, for example a transparent substrate body, is particularly preferably permeable to light of a wavelength range with which the master holograms are exposed. A transparent material can also be colored to select light radiation of a specific wavelength.

[0051] A "master hologram" within the meaning of the invention is preferably a holographic-optical element comprising at least one hologram to be replicated. The master hologram is designed for an optical function (e.g., diffraction, reflection, transmission, and / or refraction) for one or more wavelengths. For this purpose, for example, several holograms, each diffracting light of one wavelength, and / or multiplex holograms diffracting light of multiple wavelengths, can be arranged as hologram stacks. The master hologram can, for example, be a diffractive optical element (DOE). Diffractive optical elements (DOEs) utilize a surface relief profile with a microstructure for their optical function. Alternatively, the microstructure can also be present in the volume of the element in the form of a local difference in the refractive index.The light transmitted through a DOE can be converted into almost any desired distribution through diffraction and subsequent propagation. This can be an image, a logo, text, a refraction pattern, or similar. Furthermore, the master hologram can be a technical hologram, such as a Bragg mirror, a diffuser, or a hologram acting as a lens.

[0052] The process for producing the master hologram may preferably be referred to as "hologram origination" or "hologram mastering." The master hologram can be created using an analog or digital process. In an exemplary analog process, a first coherent beam, the object beam, is reflected from an object and onto a recording material, which is simultaneously exposed to a second coherent beam, the reference beam. The object beam and the reference beam interfere, creating an interference pattern on the recording material. This interference pattern, or fringe pattern, is recorded by light-sensitive material, which, after processing, takes the form of a surface relief pattern on a surface of the material or of spatially varying refractive indices just a few micrometers below the surface.To view an image of the original object, the master hologram can be illuminated with light diffracted by the recorded surface relief pattern or refractive index pattern. This diffracted beam contains the image of the original object. The master hologram can then be used as a new object when creating further copies with the same image. The master hologram can also preferably be computer-generated. The microscopic gratings that create the diffraction effects can be produced, for example, by laser interference lithography. In this technique, two or more coherent light beams are configured to interfere at the surface of a recording material. The positions of the light beams relative to the recording material can be controlled by a computer. Depending on the strength of the laser, the recording material can be made of almost any material.Other techniques such as electron beam lithography can also be used to digitally create the master hologram. The master hologram can preferably comprise glass, silicon, quartz, UV varnish, a photopolymer composite, and / or a metal such as nickel.

[0053] An "optically accessible surface" within the meaning of the invention is a surface that is at least 50%, preferably at least 60%, 70%, 80% or 90%, and particularly preferably 100%, not covered by an optically absorbing material. In particular, an optically absorbing material is not present between the surface in question and a light source for exposure. In some cases, depending on the shape of the master element, an opaque frame of the carrier means can cover part of the optically accessible surface. Preferably, the frame covers no more than 50%, more preferably no more than 40%, 30%, 20%, or 10% of the optically accessible surface. An optically accessible surface is also preferably low-reflective.It may be preferred that the optically accessible surface has a visible light reflectance at a normal angle of incidence of less than 50%, preferably less than 40%, less than 30%, less than 20%, or less than 10%. In some preferred embodiments, an optically accessible surface has an anti-reflective (AR) coating. This can increase the utilization of the incident light for exposing the composite web.

[0054] In a preferred embodiment of the invention, the master elements are separated in the first carrier means along a linear arrangement. The carrier means can therefore preferably form a buffer distance between adjacent master elements. Advantageously, the buffer distance prevents unwanted propagation or scattering of light from one master element to an adjacent master element from impairing the replicated hologram. At the same time, the distance can facilitate handling of the replicated holograms. On the one hand, the separation of the respective holograms is easier. On the other hand, even after cutting apart, a small edge can remain free around the hologram, which allows the hologram to be transported without touching the image content. The risk of damage to the finished replicated holograms is reduced and the quality increased.Preferably, the master elements are separated by light-absorbing spacers. This protects the master holograms and the portion of the composite web lying on them from stray light or from light used to expose an adjacent master hologram. If unwanted light reaches the wrong areas of the composite web, it can be exposed with undesirable patterns that overlay the replicated image and reduce its quality. For example, if a first master element is exposed by light directed onto its side surface without a light-absorbing barrier in place, the light can reach a second master element arranged in a row adjacent to the first. The second master element can thus be exposed from an unsuitable angle, creating an unintended ghost image on that portion of the composite web.This phenomenon is called "cross-talk" and is particularly effectively prevented by using light-absorbing spacers.

[0055] By integrating the light-absorbing spacer into the carrier material, the outward-facing side surfaces and the top surface of the master elements can also be kept optically accessible. Furthermore, the substrate body of the master elements can advantageously be kept completely transparent from all sides. This is particularly advantageous for enabling exposure from various orientations, for example, for transmission or reflection, possibly in an edge-lit or back-lit configuration.

[0056] Alternatively or additionally, it may be preferable to apply a light-absorbing layer to vertical surfaces of the master elements. A light-absorbing layer can be much thinner than a spacer of the carrier material. This allows multiple master elements to be exposed side by side without causing optical interference, while simultaneously maintaining a minimal buffer distance or a nearly continuous effect in a replicated hologram composed of multiple components of the different master holograms.

[0057] This advantageously enables a nearly seamlessly replicated (complete) hologram with large dimensions and high image quality without the need for an equally large master element. Furthermore, small changes can be made to a portion of the hologram without requiring the replacement of all master elements. One area of ​​a replicated (complete) hologram that needs to be changed between runs could, for example, concern the (national) language of a text element used in a car's head-up display. As another example, the required arrangement or orientation of the master elements can also vary depending on whether the head-up display is for a left-hand drive or a right-hand drive vehicle of the same model.The method according to the invention, which utilizes a type case principle in which individual master elements can be easily exchanged accordingly, allows such adaptations to be implemented quickly and cost-effectively.

[0058] A thickness of the light-absorbing layer is preferably up to 5 mm, preferably up to 3 mm and more preferably up to 1 mm and / or preferably at least 10 pm, preferably at least 100 pm, particularly preferably at least 500 pm.

[0059] Preferably, the first carrier means is mounted so as to be tiltable and / or height-adjustable, wherein the device for replicating the master holograms preferably comprises means for adjusting the angle of inclination and / or height of the first carrier means. Such means can also be referred to as an alignment unit for the first carrier means within the meaning of the invention and are known to those skilled in the art. Exemplary means for adjusting the height of the first carrier means comprise an adjustment table with actuators for up and down movement. Thus, the first carrier means and the master elements contained therein can be brought into contact with another process component, in particular a composite web, an optical adhesive film, a lamination roller, and / or one or more coupling elements.

[0060] Means for adjusting an angle of inclination can preferably also comprise an adjustment table, in which an angle of inclination of the first support means, for example, with respect to a plane of the composite web, can be adjusted by means of appropriate actuators. This advantageously ensures a particularly plane-parallel alignment of the master elements located within the first support means to the composite web or to the coupling elements (described further below). The rotation of the entire first support means allows for a uniform alignment of the master elements.

[0061] The means for adjusting an angle of inclination and / or height adjustment of the first support means preferably allow a fine adjustment with an accuracy of the height adjustment of at least 10 pm, preferably at least 5 pm and / or an adjustment of the angle of inclination with an accuracy of at least 0.1 °, preferably at least 0.01 °.

[0062] Alternatively or additionally, the other process components are mounted in a height-adjustable manner to ensure sufficient contact between the process components for carrying out the replication process. The other process components can include: transport rollers or transport components for positioning the composite web, any coupling elements, a lamination roller, a dosing unit for applying an optical fluid, or a roller for applying an optical adhesive film. These components are explained in more detail below. The height adjustability of the process components preferably enables fine adjustment of their positions with a height adjustment accuracy of at least 10 μm, preferably at least 5 μm.

[0063] In a preferred embodiment, the first support means is spring-mounted. The spring-mounting can be active or passive and is preferably designed to tolerate an up-and-down movement of the first support means. The spring-mounting is preferably mechanical, (electro)magnetic, hydraulic, or pneumatic, with pneumatic spring-mounting being particularly preferred. The spring-mounting is preferably configured for a height adjustment of at least 20 μm, preferably at least 50 μm, particularly preferably at least 100 μm, and / or of at most 1000 μm, preferably at most 500 μm, particularly preferably at most 200 μm.

[0064] Preferably, the springing of the first carrier means is pressure-controlled, in particular to establish and maintain a preferred pressure between the laminating roller and the respective master elements. The spring-loaded mounting of the first carrier means preferably enables the first carrier means to be brought into contact with a further process component while simultaneously compensating for any tolerances in the height of the surface of the master elements. Advantageously, by providing a spring-loaded first carrier means during the replication process, any height differences between individual master elements located within the first carrier means can also be compensated for. An inclination of the first carrier means can also be compensated for. As explained in more detail below, it may, for example, be preferable to use a laminating roller to apply a composite web to the master elements.For this purpose, the laminating roller preferably successively sweeps over the composite web and the underlying master elements, with the spring-loaded mounting of the first carrier means ensuring optimal height and pressure conditions for each of the master elements being swept over. The spring-loaded mounting allows the first carrier means to move slightly up and down, for example, synchronously with the laminating roller to compensate for height differences between the master elements. This allows all master elements to be brought to the exact required height.

[0065] Manufacturing tolerances or damage to the surface of the master elements can also be compensated. Air gaps or bubbles between the surface of the master elements and the composite web and / or the coupling element are eliminated, and the optical contact between the master elements and other process components is improved.

[0066] In a further preferred embodiment of the invention, the master elements can be positioned in the first support means in a spring-loaded manner. Thus, the first support means can preferably also comprise means for individually springing the master elements, in particular independently of one another. For example, a base of the first support means can be provided with an elastic material, such as a foam.

[0067] This allows variations in the dimensions of the master elements within the first carrier means to be compensated so that, for example, the composite web can be clamped seamlessly between planar coupling elements and the master elements.

[0068] In a preferred embodiment of the invention, the method further comprises arranging one or more optically transparent coupling elements on the laminated composite web such that a portion of the composite web is enclosed between the one or more coupling elements and the master elements during exposure.

[0069] For the purposes of the invention, a "coupling element" is preferably a three-dimensional block made of transparent material with a refractive index and dimensions configured to direct the exposure beams toward and / or away from the master holograms. The coupling element can preferably have any three-dimensional shape, in particular a cuboid shape, a wedge shape, a cylindrical shape, a prismatic shape, and / or a prismatic shape with a semicircular or semi-elliptical cross-section. The coupling element can preferably have various optically accessible surfaces. Preferably, at least one side surface or base surface and one underside or lateral surface of the coupling element are optically accessible. Preferably, an optically accessible surface of the coupling element is also low-reflective.It may be preferred that the optically accessible surface has a visible light reflectance at a normal angle of incidence of less than 50%, preferably less than 40%, less than 30%, less than 20%, or less than 10%. In some preferred embodiments, an optically accessible surface has an anti-reflective (AR) coating. This can increase the utilization of the incident light for exposing the composite web.

[0070] The coupling element can be used to direct an exposure beam onto a side surface above a master hologram. The angle of the exposure beam can be selected so that it also passes through a lower surface of the coupling element and reaches the master hologram before being reflected back by the composite sheet. The reflected light is directed by the coupling element in such a way that it does not impinge on adjacent parts of the composite sheet and its scattering is minimized. Alternatively, the light can also be guided through the master hologram to expose a transmission hologram in the composite sheet. The coupling element can also be used to hold the composite sheet in place via the surface of the master elements. Since the coupling element does not need to be replaced between series, a single plate can be used to cover all linearly arranged master elements in the carrier medium.This eliminates the risk of edges of the coupling elements leaving marks on the composite sheet. It also simplifies the alignment of the coupling element over the support material.

[0071] However, it may be preferable to use multiple coupling elements. This reduces the size and weight of each coupling element and facilitates storage and replacement. This also offers advantages in the quality of the coupling elements, as polishing systems often have a maximum size limit for the materials used. A high degree of polishing can be achieved by limiting the dimensions of the coupling element in this way.

[0072] It can be particularly advantageous if a contact surface of the coupling elements with the composite web has the same length and width as a contact surface of the master elements with the composite web and is arranged directly opposite them. This enables a precise alignment of the two elements, and if the coupling elements were to leave imprints or traces on the composite web, these would be located in the buffer area between replicated holograms. In preferred embodiments, the coupling elements and master elements can have an identical substrate body in terms of size and shape. In this way, the substrate bodies can be manufactured and stored more cost-effectively in larger quantities.

[0073] In a further preferred embodiment of the invention, each master element is assigned a coupling element. Preferably, at least one lower surface of the respective coupling element is congruent with an upper surface of the corresponding master element.

[0074] In a further preferred embodiment of the invention, the coupling elements are arranged on a height-adjustable second support means. The second support means can be configured analogously to the first support means. In particular, the second support means—analogous to preferred embodiments of the first support means—is mounted so as to be tiltable and / or height-adjustable. Likewise, a spring-loaded up-and-down movement of the second support means can be preferred. It can be preferred for the second support means to comprise light-absorbing spacers between the coupling elements. This can prevent the light beams from reaching adjacent coupling elements or being reflected into adjacent parts of the composite web. By means of the height-adjustable second support means, the coupling elements can be brought into contact with the composite web, preferably after lamination of the composite web and before its exposure.

[0075] It may be preferred for the lamination to take place in the same section of the composite web as the exposure. During lamination, the second carrier means with the coupling elements can be held at a distance from the composite web (first height). The lamination of the composite web can be carried out using a roller which is lowered onto the composite web and rolls over the composite web to bring it into close contact with the aligned horizontal surface of the master elements. The lamination roller and / or the master elements can preferably be spring-loaded to maintain contact between both components despite variations in the surface position or surface quality of the components. The lamination roller can then be raised or retracted so that the coupling elements can subsequently be lowered to establish contact with the composite web (second height).In the position of the coupling elements, the composite track is clamped between the coupling elements and the master elements.

[0076] Exposure can be performed using both the master elements and the coupling elements. After exposure is complete, the coupling elements can be raised again to a first height position at a distance. Optional fixation can be performed in place, and the composite web can be detached from the surface of the master elements, e.g., by one or more other rollers lifting one or more parts of the composite web that lie outside the first support means for the master elements from below. The first support means remains accessible so that the order of the master elements can be changed. In this way, several process steps can be performed in a single area. This increases the compactness of the process and the device used for it.

[0077] In a preferred embodiment of the invention, the same coupling element is used for the exposure of different master elements. In this case, a contact surface of the coupling element can cover the surface of all master elements in the first carrier means for the exposure. For example, a coupling element in the form of a cuboid coupling plate can be used, the length of which extends over all master elements. Alternatively, a coupling element can be moved over the surface of the master elements, wherein exposure preferably takes place in synchronization with the movement of the coupling element. The movement of the coupling element can preferably be a pushing or rolling movement. The one or more coupling elements are preferably configured such that only a limited area is in contact with the composite web during exposure.This surface is preferably referred to as a "contact surface" within the meaning of the invention. Particularly in the case of a coupling element designed to roll over the composite track, the contact surface of the coupling element can constantly shift while remaining constant in size.

[0078] In preferred embodiments of the invention, the contact surface of the coupling element is curved or planar. When using curved contact surfaces, a lens effect is preferably avoided. Depending on the application, the use of curved or planar surfaces may be preferred, as explained below.

[0079] In a further preferred embodiment of the invention, a coupling element has a cylindrical shape. Such a coupling element can preferably function as a roller and be rolled or pushed over the composite web. Thus, the cylindrical coupling element can establish optical contact along an axis with the composite web. Light from a lateral surface and / or a base surface can be directed via the coupling element onto the composite web and the master elements. Preferably, a light source and / or a light-deflecting component moves synchronously with the coupling element to illuminate the master elements.

[0080] In a further preferred embodiment of the invention, the cylindrical coupling element is mounted analogously to a lamination roller, wherein the cylindrical coupling element is preferably mounted in a height-adjustable, height-adjustable, spring-loaded, and / or pressure-controlled manner. Such a mounting can improve the optical contact between the coupling element and the composite web as well as the master elements. In addition, one or more mounting rollers, preferably three mounting rollers, are preferably provided for the mounting and / or movement of the coupling element.

[0081] In preferred embodiments of the invention, the cylindrical coupling element itself functions as a lamination roller, or vice versa. Thus, the cylindrical coupling element can also improve mechanical contact between the composite web and the master elements. With this arrangement, lamination preferably takes place synchronously with exposure. A separate lamination roller can be omitted. This saves space and increases the throughput of the process. A further advantage of using a cylindrical coupling element is the small contact area between the coupling element and the composite web. Such a small contact area is particularly advantageous when using an optical fluid between the coupling element and the composite web. Firstly, the amount of optical fluid used can be kept low.Secondly, the forces required to remove the coupling element from the composite web are also reduced. Removal of the cylindrical coupling element can thus be carried out with particular care for the composite web. This will be explained in more detail with regard to the use of optical fluids.

[0082] In a further preferred embodiment of the invention, the coupling element has a prismatic shape with a semicircular cross-section. The shape of such a coupling element can preferably correspond to the lower half of a roller and have two lateral surfaces: a curved lateral surface and a planar lateral surface. Preferably, the curved lateral surface is brought into contact with the composite web on the surface of the master elements and pushed over this surface. In this way, the weight of the coupling element can be kept low. The coupling element also has a narrow contact surface with the composite web, which is advantageous when using optical fluids. When exposing such a coupling element, a lens function should preferably be avoided.

[0083] In a further preferred embodiment of the invention, a coupling element has a prismatic shape with at least one planar surface, which preferably serves as a contact surface for application to the composite sheet. The cross-section of the coupling element preferably tapers towards the planar contact surface, so that the prismatic shape can also be referred to as a wedge shape within the meaning of the invention. For example, the coupling element or at least a portion of the coupling element can have the shape of an isosceles trapezoid in cross-section, with the smaller base side of the trapezoid being brought into contact with the composite sheet as a planar surface.This embodiment allows the contact area between the coupling element and the composite track to be optimally adjusted, in particular, even larger than would be the case with a cylindrical coupling element, where the contact area essentially corresponds to a line depending on the degree of curvature. Particularly when using an optical fluid, a larger contact area can be maintained smoothly and seamlessly when the coupling element is displaced. Increased capillary forces between the contact element and the composite track advantageously prevent the formation of air gaps, thus ensuring particularly good optical contact.

[0084] In a further preferred embodiment of the invention, contact between the coupling element and the composite web on the surface of the master elements occurs with a predetermined pressure. For this purpose, pressure force sensors or pressure sensors for measuring a pressure force or pressure between the coupling element and the master elements are preferably provided. A film coating can preferably be used as a sensor for the pressure exerted by one process component on another, with a pressure sensor distributed over the entire film (so-called "pressure measuring film"). Such a pressure measuring film is preferably applied to an area of ​​the process component that is not used for exposure, for example, an edge area, and is particularly compact.

[0085] In a further preferred embodiment of the invention, a lower surface of the coupling elements is formed by a deformable, transparent coupling section. The use of such a deformable coupling section is particularly preferred in embodiments of the invention in which the coupling elements are only moved up and down relative to the master elements. Coupling elements with deformable coupling sections are preferably neither rolled nor displaced over the surface of the composite web in contact with the master elements.

[0086] For the purposes of the invention, a "coupling section" is preferably a part of the coupling elements that consists of a transparent, deformable material and is designed to ensure complete optical contact between the coupling element and one or more master elements. Preferably, the refractive index of the coupling section is identical to or within a range of + / -20%, preferably + / -10%, and more preferably + / -5% of the refractive index of the main body of the coupling element, the composite sheet, a top cover of the master element, the master hologram, and / or the substrate body of the master element.

[0087] The deformability of the coupling section allows it to be pressed onto the composite sheet while the composite sheet is on the aligned surface of the master elements, leaving no gaps or bubbles. This ensures particularly homogeneous optical contact between the three elements of the sandwich. Unwanted optical aberrations or patterns are avoided, resulting in a higher quality final product.

[0088] In a further preferred embodiment of the invention, a material of the coupling section is selected such that it has a shear modulus of at least 10 kPa, preferably of at least 100 kPa and even more preferably of at least 1 MPa. It may also be preferred that the material of the coupling section has a modulus of elasticity between 1 MPa and 50 MPa. It may also be preferred that the material has a refractive index between 1.4 and 1.6. Silicone has proven to be a particularly suitable material for achieving a sufficient refractive index and at the same time being sufficiently elastic, easy to clean and leaving no residues on the composite web. Additionally or alternatively, it may be preferred that an optical fluid is applied to the horizontal surface of the master elements and / or the composite web.This can have a refractive index close to that of the substrate body of the master elements, the coupling element, and / or the composite track to ensure uninterrupted light transmission. The optical fluid can also improve the optical contact between the elements by compensating for any wedge defects, surface tolerances, or damage. Air gaps or bubbles between the process components can also be filled to prevent unwanted reflections at interfaces between the components.

[0089] In a further preferred embodiment of the invention, a dosing unit is provided for dosing the optical fluid. The dosing unit is preferably configured for applying a predetermined amount of an optical fluid to a process component. The dosing unit is preferably configured, in particular, for applying an amount of optical fluid to the composite web that is sufficient to completely fill a gap between the coupling element and the composite web.

[0090] In a further preferred embodiment of the invention, the dosing unit is mounted so that it can be adjusted in height. The dosing unit can thus be brought close to a surface of a process component, e.g., the composite web, for precise application of the optical fluid and then removed to create space for additional process components such as coupling elements or light sources.

[0091] In a further preferred embodiment of the invention, an optical fluid is introduced between the composite web and a coupling element. The amount of optical fluid used is preferably designed to cover a contact area between the coupling element and the composite web. The optical fluid preferably adheres to the surfaces of the coupling element and the composite web by means of capillary forces. Larger contact areas between the coupling element and the composite web generate greater forces. This is advantageous for maintaining optical contact during movement of the coupling element across the composite web.

[0092] The coupling element is preferably removed from the composite web after exposure in such a way that the adhesive forces on the composite web are minimized.

[0093] In a preferred embodiment of the invention, the coupling element is moved horizontally in the plane of the composite web—preferably transversely to the flow direction of the composite web—before the coupling element is removed from the composite web by a vertical movement. Such a movement in the plane of the composite web can be a transverse, oblique, or rotational movement. The movement is preferably designed to reduce the contact area between the coupling element and the composite web without a vertical movement occurring. This effectively prevents unwanted force transmission to the composite web.When using a coupling element with a curved contact surface - for example when using a cylindrical coupling element - such a movement for removing the coupling element can preferably be omitted, since the narrower contact surface reduces the risk of deformation or distortion of the composite web.

[0094] In a further preferred embodiment of the invention, an optical adhesive film is temporarily inserted between two process components of the method. For example, the optical adhesive film can be inserted between a master element and the composite web and / or between the composite web and a coupling element.

[0095] For the purposes of the invention, an "optical adhesive film" is preferably a transparent film with a refractive index close to the refractive index of the master element, the composite web, and / or the coupling element. The optical adhesive film is preferably designed to improve optical contact between two exposed process components, so that reflections at the interface between the process components are reduced or eliminated.

[0096] Preferably, the materials used for the optical adhesive film have identical or similar optical properties to those used for the substrate of the master element (or the coupling element or its coupling section) and / or the composite web. The similar or identical properties preferably include transparency, haze, stress birefringence properties, and / or the refractive index. The use of identical or similar materials enables a very close match of the refractive index of the optical adhesive film to the refractive indices of the adjacent process components, ensuring a transition between the adjacent refractive indices without refractive index jumps.Reflections at the interface between the master element (or the coupling element), the optical adhesive film and / or the light-sensitive composite sheet are thereby largely eliminated or significantly minimized.

[0097] In a preferred embodiment of the invention, a refractive index difference between the surface (or a cover) of the master element and the optical adhesive film and / or between the optical adhesive film and a surface of the photosensitive composite web is not more than 0.2, preferably not more than 0.1, and more preferably not more than 0.05. Likewise, in the case where the optical adhesive film is placed between the photosensitive composite web and a coupling element, the difference between the refractive index of the optical adhesive film and an adjacent surface of the coupling element is preferably not more than 0.2, more preferably not more than 0.1, and even more preferably not more than 0.05.

[0098] In a further preferred embodiment of the invention, the refractive index of the optical adhesive film lies between the refractive index of the surface of the master element and the refractive index of a surface of the photosensitive composite web. If the optical adhesive film is arranged between the photosensitive composite web and a coupling element, the refractive index of the optical adhesive film preferably lies between that of the photosensitive composite web and that of the coupling element. In this context, the term "between" preferably also includes the values ​​of the refractive indices of the adjacent process components themselves. This arrangement enables a smooth or interference-free transition of light rays between the various process components with minimal reflections and / or aberrations at interfaces.

[0099] Furthermore, the optical adhesive film is preferably a solid in which the Brownian motion is sufficiently small, preventing any "wobble" in the phase of the light and thus resulting in a more stable interference field in the hologram copy within the exposure time. This prevents the microstructures from blurring, maximizing the diffraction efficiency of the holograms. The sharpness and contrast of the resulting hologram are also significantly improved. The optical adhesive film improves the optical contact between exposed transparent components through which the exposure light is passed. This reduces unwanted reflections, scattering, or losses and increases the quality of the reproduced hologram.

[0100] The optical adhesive film can be shaped analogously to the composite web and moved through the process in a similar manner, e.g., using rollers. This allows for easy synchronization of the optical adhesive film with the composite web. It is also possible and may be preferred for the optical adhesive film and / or the light-sensitive composite web to be applied to the surface of the master element or the surface of the coupling element by a laminating roller. The same roller can be used for laminating the composite web and the optical adhesive film.

[0101] In contrast to the OCAs (optical clearance adhesives) commonly used in optical displays, the optical adhesive film preferably exhibits low adhesive strength in addition to its advantageous optical properties. This allows the optical adhesive film to be removed from a surface after use without leaving residue and with little force.

[0102] In a preferred embodiment of the invention, the optical adhesive film comprises at least one adhesive layer. The at least one adhesive layer preferably has a peel force relative to the surface of the master element and / or the coupling element and / or a surface of the photosensitive composite web of less than 3 N / cm (Newton per centimeter), preferably less than 1 N / cm. In preferred embodiments, however, the peel force of the adhesive layer of the optical adhesive film relative to the surface of the master element and / or the coupling element and / or a surface of the photosensitive composite web is at least 0.01 N / cm, preferably at least 0.1 N / cm. The peel force of the optical adhesive film or one of its layers can be measured, for example, according to a 180-degree peel test. In preferred forms, the measurement is carried out according to ASTM D903.

[0103] In a preferred embodiment of the invention, the optical adhesive film has a single-layer structure, wherein the structure comprises exactly one adhesive layer. The precisely one adhesive layer is preferably adhesive on both sides to facilitate optical contact.

[0104] In a preferred embodiment of the invention, the optical adhesive film comprises two adhesive layers, with each adhesive layer preferably being applied directly to a carrier layer, so that the optical adhesive film comprises three layers. Such an optical adhesive film can adhere to two surfaces simultaneously, thereby providing particularly good optical contact and reducing the risk of air gaps or unwanted reflections.

[0105] In a preferred embodiment, the method is carried out using a device, the device comprising an unwinding roller for unwinding the optical adhesive film and a take-up roller for rewinding the optical adhesive film after use. The method preferably comprises a step of removing the optical adhesive film from the relevant process component after exposure. Preferably, the device also comprises a lamination roller for temporarily laminating the optical adhesive film to the surface of a master element, a composite web and / or a coupling element. Preferably, the optical adhesive film can be provided with protective layers on one or both sides. The device can comprise take-up rollers for removing the protective layers before use of the optical adhesive film.In a further preferred embodiment of the invention, the first support means is designed such that master elements of different shapes and / or sizes can be arranged therein. For example, one or more frame elements and / or spacers of the support means can be arranged displaceably and / or clampably. The first support means can also be designed such that it can accommodate master elements of different thicknesses. To bring the upper surfaces of the master elements to the same level, filler substrate blocks can be attached beneath one or more master elements.

[0106] In a further preferred embodiment of the invention, the substrate bodies of the master elements have the same dimensions. Preferably, the substrate bodies have a cuboid shape. The use of identical square shapes for the master elements has proven particularly simple for aligning the master elements in the first carrier. However, the use of different shapes is also possible, with the shapes or dimensions varying particularly along the film web. Different shapes of the substrates of the master elements are also possible perpendicular to the film web, but are less preferred due to lower material utilization.

[0107] In a further preferred embodiment of the invention, the substrate bodies preferably have a height between 1 - 10 cm, a length between 3 - 20 cm and a width between 3 - 20 cm.

[0108] While the method according to the invention can in principle use master elements of any size, a height of at least 1 cm has proven to be preferred, as this provides sufficient surface area on the side of the master elements for exposure. The preferred heights also make exposure from different angles easy to achieve in order to meet different requirements for hologram replication. Furthermore, the preferred dimensions ensure sufficient robustness with a compact size to enable easy replacement. The preferred lengths and / or widths of at least 3 cm also enable sufficiently economical use of the composite web, particularly if there is a buffer distance between the master elements. In addition, the dimensions are suitable for capturing the image or pattern to be copied for applications such as banknote printing.Although the lengths and / or widths of the substrate bodies are also not limited, substrate bodies with a length and / or width of up to 20 cm can reduce production costs and achieve particularly easy handling.

[0109] In a further preferred embodiment of the invention, the at least two optically accessible surfaces of the master elements are polished, wherein the degree of polishing is preferably at least P3. In a further preferred embodiment of the invention, the optically accessible surfaces of the coupling elements are also polished, wherein the degree of polishing is preferably also at least P3.

[0110] When a surface of the coupling element is brought against a surface of the master element via the composite track, it is advantageous for both surfaces to be polished. It is also preferred that any wedge error of the master elements and / or the coupling elements individually and relative to each other be reduced as much as possible. Parallel displacement of the coupling elements with respect to the master elements could impair the surface optical contact in the event of an undesired wedge.

[0111] In a further preferred embodiment of the invention, the substrate bodies of the master elements are formed from a material that is an optical plastic. The material of the substrate bodies is preferably selected from the following group: polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin polymers (COP), cycloolefin copolymers (COC), and / or an optical glass, preferably selected from the group comprising borosilicate glass, quartz glass, B270, N-BK7, N-SF2, P-SF68, P-SK57Q1, P-SK58A, and / or P-BK7.

[0112] Preferably, both the substrate body and any cover of the master element have a refractive index between 1.4 and 1.6.

[0113] The choice of material for the substrate body may depend on the desired exposure angle, any height restrictions, and the resulting desired refractive index. It may also be preferable for a substrate body to be colored, for example, to filter light wavelength-selectively to create a hologram with a specific wavelength. In this way, a broadband light source can be used to expose different master holograms.

[0114] In a further preferred embodiment of the method, a selection and optionally the arrangement of the sequence of master elements is controlled by a control unit.

[0115] The term "control unit" preferably refers to any computer unit with a processor, a processor chip, a microprocessor, or a microcontroller that enables automatic control of the components of the device, e.g., a rotation speed of an unwind roll, a rewind roll, a lamination roll, a transport roll, the movements of a pick-and-place robot for the master elements, an alignment unit for the master elements or the carrier means, a lamination temperature, a lamination pressure, an orientation and / or scanning speed of a light source, a wavelength of the light source, a fixation intensity, etc. The components of the control unit can be conventional or individually configured for the respective implementation.Preferably, the control unit comprises a processor, a memory and computer code (software / firmware) for controlling the components of the device.

[0116] The control unit may also comprise a programmable circuit board, a microcontroller, or other device for receiving and processing data signals from the components of the device, for example, from sensors relating to the identity or type of a master element, as well as other relevant sensory information. The control unit preferably further comprises a computer-usable or computer-readable medium, such as a hard disk, random access memory (RAM), read-only memory (ROM), flash memory, etc., on which computer software or code is installed. The computer code or software for controlling the components of the device may be written in any programming language or model-based development environment, e.g., without limitation, C / C++, C#, Objective-C, Java, Basic / VisualBasic, MATLAB, Python, Simulink, StateFlow, Lab View, or Assembler.

[0117] The term "control unit is configured to" perform a specific process step, such as exposing a master element at a specific angle by changing the speed of one or more drive motors, may include custom or standard software installed on the control unit that initiates and controls these operational steps.

[0118] The control unit preferably comprises a processor and a memory. The processor preferably reads sequence data from the memory and signals to an actuator and / or a user the sequence in which the master elements are to be arranged. Thus, the control unit can preferably ensure that the master holograms are arranged in the first carrier means according to a predetermined sequence, such as a sequence in which larger components incorporating the replicated holograms are processed on a parallel production line.

[0119] It may be advantageous for the control unit to instruct an actuator to move the next master element or the next n master elements in the sequence closer to or into the first carrier means, where n is preferably the number of master elements that the first carrier means can accommodate. The actuator may preferably be a logistics dolly, another conveyor belt, a turntable, or a pick-and-place robot, to name just a few examples. In this way, the placement of the master elements in the correct sequence can be partially or fully automated, reducing the risk of human error.

[0120] It may also be preferred that the control unit be configured to signal the next master element or the next n master elements to a user. This can be done in various ways, e.g., visually or acoustically. As an example of a visual signal, the control unit can be configured to activate a light at the storage location of the next master element, e.g., on the corresponding shelf, box, trolley, etc.

[0121] Preferably, the control unit comprises an interface for signaling the sequence to a user. The processor may thus be configured to read sequence data from the memory and instruct the interface, e.g., a screen, to display all or a relevant portion of the sequence data. The sequence data may preferably include information about the following:

[0122] - the identities or types of the master elements to be exposed and their order,

[0123] - a matrix arrangement of the master elements in the first carrier means, for example a row and column number,

[0124] - one or more wavelengths with which the master element is to be exposed,

[0125] - a light intensity with which the master element is to be exposed,

[0126] - the angle from which the master element is to be exposed and / or the angular position and path of the light source,

[0127] - the type of hologram to be created, for example a reflection or transmission hologram.

[0128] This list is neither exhaustive nor exclusive, but merely exemplary.

[0129] In a further preferred embodiment of the invention, exposure instructions for the sequence are stored in the memory. Preferably, the processor signals a user and / or an actuator to adjust the position, path, and / or wavelength of a light source according to the exposure instructions. Preferably, the control unit comprises an interface for signaling the exposure instructions to a user.

[0130] In a preferred embodiment of the invention, the control unit is connected to a sensor, wherein the sensor preferably reads an ID feature of the individual master elements or a storage location of the master elements and transmits the ID to the control unit for controlling and / or monitoring the sequential arrangement.

[0131] For the purposes of the invention, an "ID feature" preferably refers to all or part of the master hologram itself, or alternatively, a QR code, a barcode, a number, a symbol, or the like, which can be permanently or removably affixed to the master element for its identification. Additionally or alternatively, the ID feature may not be located on the master element, but rather at its storage location. Preferably, the ID feature is affixed to an area of ​​the master element that does not cross the path of a light beam used for exposure. Preferably, this area is located on a different surface of the master element than the at least two optically accessible surfaces.

[0132] By controlling or monitoring the identities of the master elements placed and exposed in the first carrier means, the control unit can prevent and / or detect errors in the sequence. Preferably, the control unit can also alert a user to such errors so that corrective intervention in the production process can be made. A further advantage is that a register of the exposed holograms can be created and stored in memory. This can be used for quality control and statistical purposes. The control unit can also use this information to determine which master elements require maintenance or replacement. For example, depending on the number of uses, possibly weighted by the intensity of an exposure, the corresponding master elements can be replaced before degradation of the master elements leads to a loss of quality.

[0133] In a preferred embodiment of the invention, the method comprises arranging the master elements in two parallel rows. By using at least two rows, the size of the master elements can be further reduced while simultaneously optimizing the entire width of the composite web. If changes are required in a sub-area of ​​a larger master hologram to be replicated, these changes can also be made in smaller sections. Furthermore, the efficiency of the method can be improved because a larger number of identical or different master holograms can be replicated simultaneously.

[0134] With sufficient light intensity, it is possible to expose both rows from an optically accessible side of the master elements. This means that the light beam directed into the side surface of a master element in the first row can reach a master element in the second row located behind it in the beam direction. This further increases the efficiency of the process, as two master holograms can be replicated simultaneously using one light source.

[0135] It may also be preferable to expose each row separately, for example, with separate light sources directed at two opposite sides of the array of master elements. Preferably, the rows of master elements are separated by a light-absorbing spacer, which spacer is preferably part of the first support means. The light-absorbing spacer prevents unwanted light from penetrating one master element into another, thus avoiding optical interference such as crosstalk. This is particularly advantageous if the master elements of the different rows are to be exposed from different angles or with different wavelengths.

[0136] The exposure for replicating a master hologram using the method according to the invention can be carried out using various techniques. Hologram replication processes can be divided into relief holograms and volume holograms.

[0137] Relief holograms are formed by physical contact between a deformable sensitive layer and a master hologram, so that the diffraction pattern of the master hologram is imprinted into the sensitive layer.

[0138] A volume hologram is preferably written into a sensitive layer by the interference of two light beams (a so-called reference beam and an object beam). Preferably, a volume hologram is written into the composite web. This can preferably be done using a transmission or reflection technique. Interference of object and reference beams within the hologram volume preferably creates a sequence of Bragg planes. A volume hologram therefore preferably has a non-negligible extension in the propagation direction of the light beams, whereby the Bragg condition applies during reconstruction on a volume hologram. For this reason, volume holograms exhibit wavelength and / or angular selectivity. The ability of volume holograms to store multiple images simultaneously enables, among other things, the production of colored holograms.Light sources that emit the three primary colors blue, green, and red can be used to record holograms. These three beams preferably simultaneously illuminate a portion of the composite web at equal angles. After exposure, three holograms are stored simultaneously in the volume hologram. To reproduce the color hologram, it can be exploited that each partial hologram can be reconstructed using only the color with which it was recorded. Thus, the three reconstructed color separations overlap to create a color, true-to-original image, provided the color components are correctly weighted.

[0139] Reflection holograms are reflective holograms that reflect incoming light from the light source and thus act like a mirror. Preferably, the reference beam (preferably an incoming light beam from the light source) and the object (in this case, the master hologram) are arranged on opposite sides of the composite sheet. A reference beam penetrates the composite sheet and is then reflected by the master hologram back into the light-sensitive layer of the composite sheet. In the light-sensitive layer of the composite sheet, the reference beam and object beam overlap in different beam directions to create the replicated hologram. The master hologram can preferably be applied to a surface of the master element or integrated into the substrate body.

[0140] The light source for a reflection hologram can be arranged such that the reference beam is incident on the composite web in a desired direction, preferably in a direction that is desired for later reconstruction. In a preferred embodiment, the light source is oriented with respect to the master element such that the composite web is located between the light source and the master element. The light source can, for example, be aligned above the master element such that the reference beam is incident downwards on the composite web in a predetermined direction. The reference beam is preferably at least partially reflected by the master element in the form of an object beam back into the composite web. The reference beam and the object beam thus enter the photopolymer composite from opposite sides and interfere in its light-sensitive layer to replicate the hologram.

[0141] Transmission holograms are transmissive holograms, where the light from a light source is transmitted and diffracted by it. Preferably, the incident direction of the reference beam (preferably an incident light beam from the light source) and the object (in this case, the master hologram) are arranged on the same side of the composite sheet. An incident beam penetrates the master hologram and is separated into an (undiffracted) reference beam and an object beam. In the light-sensitive layer of the composite sheet, the reference beam and object beam overlap with the same beam direction to create the replicated hologram.

[0142] In the case of a transmission hologram, it may be preferable to arrange the light source such that the composite path can be illuminated by a reference beam and an object beam from the same side. The light source is preferably oriented with respect to the master element such that a light beam first passes through the master element and the master hologram before reaching the composite path. The light source can preferably be arranged such that it passes through a transparent master element from a side surface. The light source can also preferably be arranged such that it falls onto the composite path through an upper and / or lower surface of the master element. The incident light beam is preferably refracted by the master element such that a reference beam and an object beam are created, wherein the object beam preferably corresponds to the portion of the light that is diffracted by the master hologram.The object beam preferentially interferes with the undiffracted reference beam in the compound path to replicate the hologram.

[0143] In preferred embodiments of the invention, one or more master elements can be used to expose the composite web to replicate a transmission hologram therein. Preferably, the replicated transmission hologram can be configured to be edge-lit, so that the holographic image can be reconstructed by light from a substantially lateral direction. The replicated transmission hologram can also be configured to be back-illuminated, so that the holographic image can be reconstructed by light incident substantially from back to front. It may also be preferred that one or more master elements are used to expose the composite web and replicate a reflection hologram therein. Likewise, it may be desirable for the replicated reflection hologram to be edge-lit.Such a hologram can, for example, be used in a glass pane with concealed light sources arranged along its edges. The replicated reflection hologram can also be configured to be front-illuminated. Such a hologram can advantageously produce a holographic image when illuminated by ambient light and viewed relatively orthogonally at eye level. Multiple such holograms can also be used in a glass pane, for example of the type disclosed in WO2020157312A1, to produce a holographic image when viewed orthogonally by reflecting light from concealed light sources along a predetermined path. It can also be advantageous to use one or more master elements to expose the composite sheet to produce a hologram comprising both a reflection and a transmission hologram.

[0144] In preferred embodiments of the invention, a reference beam for exposing the holograms can be directed onto a side surface of the master elements. In other preferred embodiments of the invention, it may be preferred that, additionally or alternatively, a reference beam is directed onto an upper and / or lower horizontal surface of the master elements.

[0145] Various techniques for exposing the composite web with the master elements using different reference beam angles and for generating different types of holograms are explained in the detailed description with reference to the figures. It should be noted that these techniques can be combined with each other and with various structural arrangements of the device, if desired. An important advantage of the present invention is that several types of exposure can preferably be performed in the same device and in the same run.

[0146] Preferably, the method is carried out using a device for replicating a plurality of holograms, comprising a first carrier means for arranging a sequence of master elements from a plurality of master elements depending on a plurality of holograms to be replicated, so that upper surfaces of the master elements are aligned in a horizontal plane, a lamination module for detachably laminating a light-sensitive composite web onto the aligned upper surfaces of the master elements, and an exposure module for exposing the master elements to

[0147] to replicate master holograms in the light-sensitive composite web, and a detachment module for detaching the exposed composite web from the master elements, wherein the master elements are releasably incorporated in the first carrier means such that a sequence and / or composition of the master elements for the replication of the plurality of holograms can be varied, and wherein the master elements are further incorporated in the first carrier means such that two or more surfaces of the master elements are optically accessible for the purpose of exposure.

[0148] The average person skilled in the art recognizes that technical features, definitions and advantages of preferred embodiments of the method according to the invention also apply to the device used therefor, and vice versa.

[0149] For the purposes of the invention, a "module" preferably refers to a workstation in a continuous manufacturing process, which is preferably equipped with the necessary technical means to carry out the process step. Different modules can be separated from each other by a housing or a partition wall, but this is not necessary. For the purposes of the invention, it may be preferable for the lamination module, the exposure module, and the detachment module to be located in the same housing.

[0150] The use of this device has the advantage of allowing multiple master holograms to be exposed in a single series, while also providing great flexibility in the exposure method. By providing a large number of master elements and arranging them linearly, the size and weight of each master element can be reduced.

[0151] By using multiple smaller master elements to cover an area normally covered by a single large master element, the complexity of a system can be reduced. Minor changes or defects to one master element do not require the replacement of all master elements. This significantly reduces costs. For example, the transparent substrates used to house the master holograms can be prepared and polished more easily. The transport and storage of smaller and lighter master elements is also more economical, as they can be stacked to save space, transported without special lifting devices, and easily inserted into or removed from the device.

[0152] The lamination module preferably brings the light-sensitive material into mechanical contact with the master elements and ensures sufficient optical contact with the master holograms. By laminating the light-sensitive material instead of simply placing it on the master elements, a particularly homogeneous contact can be achieved between the master element and the light-sensitive material, effectively preventing bubbles or wrinkles. By using a composite web made of the light-sensitive material, this can be done repeatedly and efficiently across the array of master elements, allowing the composite web to flow while the array of master elements preferably remains stationary. In particular, removable lamination allows the composite web to be removed without damage or residue and passed on to further stations in a production line.The exposure module preferably directs light onto the composite web and / or master elements to replicate a master hologram in the master element into the composite web.

[0153] The detachment module preferably ensures residue-free detachment of the composite sheet from the master elements with sufficient force without damaging the sheet.

[0154] The integration of the lamination module, exposure module and peeling module into the same device makes it possible to design the device very compact, which is particularly suitable for small series and customized end products.

[0155] The lamination module preferably comprises a lamination roller. This can be accommodated in the device in a height-adjustable manner and roll along a predetermined path to press the composite web onto the upper surface of the master elements. It can be advantageous for the lamination roller to be accommodated such that it can move along a predetermined path, wherein the lamination module preferably comprises an actuator for moving the lamination roller along this path. Preferably, the path comprises a diagonal lowering of the lamination roller from a first height and a first lateral position, which is not directly above the first support means, towards an upper surface of a first master element. The path preferably also comprises a horizontal rolling movement of the lamination roller at a second height, which is lower than the first, along the upper surface of the master elements until it reaches a last master element in the sequence.The lamination roller is preferably configured to be held at the second height and in a second lateral position downstream of the last master element during an exposure process of the sequence. In a preferred embodiment of the invention, the lamination module comprises means for adjusting the height of the lamination roller. Preferably, the means for adjusting the height of the lamination roller are configured to move the lamination roller from a storage position to a laminating position on top of the master elements. This height adjustment preferably comprises a translation of the lamination roller over a distance of at least 1 cm, preferably at least 5 cm, more preferably at least 10 cm. Suitable means for such a height adjustment are known to those skilled in the art.This allows the lamination roller to be moved outside the area between the master elements and / or coupling elements and / or light source before or after lamination. This provides greater freedom in the application of the coupling elements and / or the exposure of the master elements.

[0156] In a further preferred embodiment of the invention, the means for adjusting the height of the lamination module are also configured for height adjustment of the lamination roller. Preferably, the means for adjusting the height of the lamination roller are configured to adjust the height of the lamination roller by up to + / - 50 pm, preferably + / - 100 pm, particularly preferably + / - 500 pm. The height adjustment preferably takes place with a resolution of at least 50 pm, in particular at least 10 pm. The resolution of the height adjustment preferably refers to the smallest step over which the lamination roller can be translated for height adjustment.

[0157] Such height adjustment can advantageously compensate for even the smallest variations in the position of the surface or in the surface quality of the master elements. This means that the master elements and the first carrier material themselves can only be positioned within tolerances. Due to manufacturing tolerances, the actual height of a master element can also deviate from a target height. These tolerances can be compensated for when positioning the lamination roller, so that it is always applied to the surface of the master elements with a specified pressure. Even a slight tilt of the first carrier material can be compensated for in this way, unless, as explained above, the first carrier material is designed to be tiltable anyway. These measures improve the optical contact between the composite web and the master elements and simultaneously avoid excessive lamination pressure.

[0158] In a further preferred embodiment of the invention, the laminating roller is first brought to a predetermined position on the surface of the master elements and then its height is adjusted through small movement steps. This allows the laminating roller to be brought particularly precisely onto the actual surface of the master elements. Preferably, the height adjustment of the laminating roller is pressure-controlled. One or more sensors, in particular a pressure force sensor, can be used for this purpose. Preferably, a pressure force sensor is used to determine whether a laminating roller is in contact with the surface of the master elements with a pressure within a predetermined range. The pressure sensor can, for example, be present as a film on the surface of the laminating roller.

[0159] In a further preferred embodiment of the invention, the laminating roller is spring-mounted, wherein the spring-mounted mounting is preferably configured for a height tolerance of at least + / - 50 μm, preferably + / - 100 μm, particularly preferably + / - 500 μm. Such a spring-mounted mounting can compensate for tolerances in the surface quality and / or relative positioning of the master elements and the laminating roller. The spring-mounted mounting can further eliminate air gaps and / or bubbles between the master elements and the laminating roller, thus improving the optical contact between the composite web and the master elements.

[0160] The spring-loaded mounting of the laminating roller is preferably mechanical (electromagnetic, hydraulic or pneumatic), with pneumatic suspension being particularly preferred. Preferably, the suspension of the laminating roller is pressure-controlled, in particular in order to establish and maintain a preferred pressure between the laminating roller and the master elements.

[0161] In a further preferred embodiment of the invention, the first carrier means and / or the second carrier means comprise one or more sensors for detecting contact with another process component. Preferably, a pressure force sensor is used to detect that the first carrier means is in contact with a laminating roller and / or with the second carrier means with sufficient pressure.

[0162] In a preferred embodiment of the invention, the exposure module comprises a light source.

[0163] In a preferred embodiment, a coherent light beam is emitted from the light source. Coherence preferably refers to the property of optical waves according to which there is a fixed phase relationship between two wave trains. As a result of the fixed phase relationship between the two wave trains, spatially stable interference patterns can arise. With regard to coherence, a distinction can be made between temporal and spatial coherence. Spatial coherence preferably represents a measure of a fixed phase relationship between wave trains perpendicular to the direction of propagation and is given, for example, for parallel light beams. Temporal coherence preferably represents a fixed phase relationship between wave trains along the direction of propagation and is given in particular for narrowband, preferably monochromatic light beams.

[0164] The coherence length preferably refers to the maximum path length or travel time difference between two light beams from a starting point, so that a (spatially and temporally) stable interference pattern is still created when they superpose. The coherence time preferably refers to the time it takes for the light to travel a coherence length.

[0165] In preferred embodiments, the light source comprises a laser. Particularly preferably, it is a narrowband, preferably monochromatic laser with a preferred wavelength in the visible range (preferably 400 nm to 780 nm). Non-exhaustive examples include solid-state lasers, preferably semiconductor lasers or laser diodes, gas lasers, or dye lasers.

[0166] Other light sources, preferably coherent light sources, can also be used. Narrowband light sources, preferably monochromatic light sources, such as light-emitting diodes (LEDs), optionally in combination with monochromators, are preferred.

[0167] For replication with different wavelengths, it may be preferable to provide illumination radiation in different wavelength ranges, e.g. in a red wavelength range (preferably 630 nm - 700 nm), a green wavelength range (preferably 500 nm - 560 nm) and / or a blue wavelength range (preferably 450 nm - 475 nm).

[0168] For example, a laser system comprising three monochromatic lasers or one polychromatic laser with laser emission in the red, green, or blue (RGB) range may be provided for this purpose. It may also be preferred that the light source comprises a white light laser and an adjustable wavelength filter configured to adjust the wavelength at which the composite web is exposed.

[0169] The exposure module may also include one or more motors configured to adjust an angle of the light source and / or move the light source along a path. The light source may, for example, be configured as a scanning light source. The light source may also be equipped with an axis along which it can slide. The exposure module may also include one or more mirrors, the position of which may also be adjustable, to direct the path of a light beam onto the master elements and / or the composite path. The exposure module may also include one or more lenses, for example, a diverging lens, to broaden a light beam on the master element. It may also be advantageous if the exposure module is equipped with means to adjust the intensity of the light falling from the light source onto the master elements and / or the composite path.

[0170] In a preferred embodiment of the invention, the detachment module comprises a detachment roller positioned below a height position of a composite web. Preferably, the detachment module comprises an actuator for moving the detachment roller along a path after exposure. Preferably, this path includes raising the detachment module so that an overlying composite web is also raised.

[0171] In a further preferred embodiment of the invention, the first carrier means is designed to carry at least two, preferably at least three, more preferably at least four master elements.

[0172] In a further preferred embodiment of the invention, the device comprises a transport module for transporting a photosensitive composite web over the sequence of master elements. The transport module preferably comprises one or more transport rollers, for example, a pull roller, which advances the composite web. This can result in a semi-continuous process with a roll-shaped intermediate product that can be forwarded to further workstations for cutting.

[0173] In a preferred embodiment of the invention, the device also comprises a fusing module. This makes the device even more compact and increases the quality of the final product, as fusing can occur immediately before optical or mechanical disturbances affect the newly exposed composite web.

[0174] In a further preferred embodiment of the invention, the device comprises a control unit. The control unit preferably comprises a processor and a memory, preferably configured to control the selection and optional arrangement of the sequence of master elements. The processor reads sequence data from the memory and signals to an actuator and / or a user the sequence in which the master elements are to be arranged.

[0175] Thus, the control unit can preferably ensure that the master holograms are arranged in the first carrier means according to a predetermined sequence, such as a sequence in which larger components which integrate the replicated holograms are processed on a parallel production line.

[0176] The method according to the invention is preferably carried out using a system for replicating a plurality of holograms, comprising a device as described above and a plurality of master elements. The master elements comprise a substrate body and at least one master hologram, wherein a sequence of master elements can be selected from the plurality of master elements depending on the plurality of holograms to be replicated.

[0177] Detailed description

[0178] In the following, the invention will be explained in more detail using examples and illustrations, without being limited to these.

[0179] Short description of the figures

[0180] Fig. 1 is a schematic representation of an apparatus for carrying out the method according to the invention.

[0181] Fig. 2 is a schematic representation of another preferred embodiment of the device in which coupling elements are used.

[0182] Fig. 3 is a schematic representation of a preferred embodiment of the device in which light-absorbing spacers separate the master elements and coupling elements.

[0183] Fig. 4 is a schematic plan view illustrating an exchange of master elements in a first carrier means.

[0184] Fig. 5 is a schematic plan view of an arrangement of master elements in two rows in a first carrier means.

[0185] Fig. 6 is a schematic side view of a preferred embodiment of the device in different stages: A) before lamination, B) during lamination, C) during exposure, D) after exposure, E) during detachment, F) after detachment.

[0186] Fig. 7 is a schematic frontal view of a reconstruction of an edge-lit

[0187] reflection hologram.

[0188] Fig. 8 is a schematic frontal view of a reconstruction of an edge-lit

[0189] T ransmission hologram.

[0190] Fig. 9 is a schematic front view of an exposure process for replicating an edge-lit reflection hologram using a coupling element.

[0191] Fig. 10 is a schematic front view of an exposure process for replicating an edge-lit transmission hologram using a coupling element.

[0192] Fig. 11 is a schematic front view of an exposure process for replicating a top-lit reflection hologram. Fig. 12 is a schematic front view of an exposure process for replicating a multiplex hologram comprising both a reflection hologram and an edge-lit transmission hologram.

[0193] Fig. 13 is a schematic front view of an exposure process in which a transmission hologram is exposed from below.

[0194] Fig. 14 is a schematic front view of an exposure process for replicating a multiplex hologram comprising a transmission hologram and an edge-lit reflection hologram.

[0195] Fig. 15 is a schematic front view of an exposure process in which edge-lit transmission holograms are exposed simultaneously from both sides of a first support means with two rows.

[0196] Fig. 16A - 16F show an example of the use of a wedge-shaped coupling element with an optical fluid.

[0197] Fig. 17A - 17F show by way of example the use of a cylindrical coupling element with an optical liquid,

[0198] Detailed description of the illustrations

[0199] Figure 1 shows a schematic representation of an apparatus 1 for carrying out the method according to the invention. For the sake of simplicity, the exposure and detachment modules are not shown. The figure schematically shows a first support means 10, which holds a linear arrangement of five master elements 2 such that the horizontal upper sides of these elements are flush with each other and with the first support means 10. A simple embodiment of the first support means 10 is shown, which comprises only two end blocks, which can preferably be fixed in position, for example by clamping them together or to a stationary surface. However, any embodiment of the first support means 10 can be used, e.g.a frame connected along the underside of the master elements, or an arrangement of cavities separated by webs for receiving the master elements 2, so that at least two of their surfaces are optically accessible.

[0200] Preferably, the first carrier means 10 can, for example, comprise a frame element along a lower outer edge of the master elements 2, which frame element covers no more than 50%, preferably up to a maximum of 40%, 30%, 20%, or 10% or less of the side surfaces of the master elements 2. Such side surfaces are preferably considered optically accessible surfaces within the meaning of the invention. In Fig. 1, the master elements 2 have at least three optically accessible surfaces. F1 and F2 are optically accessible side surfaces. F3 is an upper surface and is only covered by the composite web 3. However, the composite web 3 is not a light-absorbing material, so that the upper surface F3 can be considered optically accessible. The exposure of the master hologram 6 in the master elements 2 can be achieved by directing light onto one or more of these optically accessible surfaces.An unlabeled underside of the master elements 2 can also be optically accessible, particularly if a first support means 10 with a corresponding frame structure is selected. The range of angles from which exposure can occur is therefore very wide and suitable for a wide variety of exposure arrangements.

[0201] The composite web 3 is extended over the upper side of the master elements 2 and the first carrier means 10. This arrangement results from the laminating of the composite web 3 to the flush surface using the laminating module. In this case, the laminating module comprises the laminating roller 7. This can, for example, move down onto the composite web 3 from the right side of the figure, press onto the flush surface, and roll in a relative movement to the position shown on the left in Fig. 1 (see also Fig. 6 AF). To avoid optical disturbances during exposure, it is preferred that the first carrier means 10 and the laminating roller 7 either comprise a light-absorbing material or are coated with an absorber layer 5.

[0202] Fig. 2 shows a schematic representation of another embodiment of the device

[0203] 1 . The structure of the embodiment is analogous to that of the embodiment illustrated in Fig. 1 with the main difference that the coupling elements 8 are present in a linear arrangement above the master elements 2.

[0204] Although the coupling elements 8 can be manually placed on the master elements 2, it is preferable that they be supported by a second support means (not shown), such as a frame. This allows for precise and repeatable placement of the coupling elements 8. In the embodiment shown, all coupling elements 8 are the same size and shape, as are all master elements.

[0205] 2. The size and shape of the coupling elements 8 is also the same as that of the master elements 2. Each coupling element 8 corresponds to a single master element 2 and is placed directly above it so that the side surfaces of a coupling element 8 are flush with the side surfaces of the corresponding master element 2.

[0206] It is further preferred that at least two surfaces of each coupling element 8 are optically accessible. In this embodiment, the coupling element 8 is optically accessible at least from its side surfaces F4 and F5 as well as an upper surface (without reference symbol). The coupling elements 8 comprise a transparent block made of a preferably identical material to the substrate body 14 of the master elements 2. Fig. 3 shows a further preferred embodiment of the device 1. The structure of the device 1 is analogous to that of Fig. 2. The main difference is the use of light-absorbing spacers 4 between the master elements 2. These are shown in black in the figure. Although their upper side is not visible, the upper side is flush with that of the first carrier means 10 and the master elements 2. Also shown in Fig.3 shows a series of light-absorbing spacers 4 that separate the coupling elements 8 from one another, such that a lower surface of the spacer 4 is flush with a lower surface of the coupling elements 8. It is preferred that the spacers 4 are arranged between the inner side surfaces of the master elements 2 and the coupling elements 8 and in contact with them. This means that the spacers 4 are preferably arranged along the surface that separates a master element 2 from an adjacent master element 2.

[0207] Fig. 4 is a schematic plan view of a single-row first carrier means 10, which comprises four master elements A - D. The figure illustrates how easily the master elements 2 can be exchanged on the basis of the type case principle according to the invention. In this case, for example, the master element C can be removed, for example by moving it horizontally. The master element E can be inserted into the gap in the same way, for example by pushing it into the corresponding recess. The figure also shows, by way of example, the dimensions of the master elements 2. The width of a master element 2 can be, for example, approximately 80 mm, while the length can be, for example, approximately 100 mm.

[0208] Fig. 5 is a schematic plan view of a two-row first carrier 10 comprising eight master elements A-H. By providing a larger number of master elements 2 of the same size as in Fig. 4, the process can be accelerated because more holograms can be produced per pass. The size of the first carrier 10 is adapted to accommodate a larger number of master elements 2 in two rows.

[0209] Fig. 6 is a schematic side view of another embodiment of an apparatus for performing different process steps during replication of the holograms

[0210] Figure 6A shows the positions of the various elements of the device shortly before the start of a lamination step. Before lamination begins, the master elements A, B, C, etc. are placed in a linear arrangement in the first support means 10. In this case, the support means 10 comprises only a single row. The number of master elements 2 arranged in the single row and their length determine the repeat length 20. The arrows on the laminating roller 7 in Figure 6A indicate that the laminating roller 7 moves vertically (up / down). To allow flow of the composite web 3 between passes, the laminating roller 7 is advantageously located in a first position above the first support means 10 and above the composite web 3, so that no friction between the laminating roller 7 and the composite web 3 hinders the movement of the composite web.It is also preferred that the laminating roller 7 is laterally positioned during the flow of the composite web 3 so that it is located outside the space between the coupling elements 8 and the master elements 2. This allows free vertical movement of the coupling elements 8 in the space between them and the master elements.

[0211] At the beginning of the lamination process, the laminating roller 7 is lowered to a second height so that it reaches the level of the aligned horizontal surfaces of the master elements 2.

[0212] As also shown in Fig. 6A, the coupling elements 8 in this embodiment comprise a lower coupling section 9. The coupling section 9 consists - in contrast to the main body of the coupling element 8, which is rigid - of an elastic, transparent material such as silicone.

[0213] Fig. 6B shows the positions of the various elements of the device 1 during the lamination process. The laminating roller 7, which encloses the composite web 3 between itself and the first carrier means 10 and / or the master elements 2, rolls horizontally in an upstream direction (to the left in the figure). This can result in a preceding roll of the composite web 3 being passively unrolled. The lamination brings the composite web 3 into optical contact with the upper surfaces of the master elements 2. During the horizontal movement of the laminating roller 7, the coupling elements 8, which are housed on a second carrier means (not shown), can be lowered. Preferably, the speed of lowering the coupling elements 8 and / or the speed of rolling the laminating roller 7 are coordinated to ensure rapid application of the coupling elements 8 without the risk of mutual interference.

[0214] Fig. 6C shows the positions of various elements of the device during exposure. The coupling elements 8 are lowered so far that the coupling sections 9 come into contact with the composite web 3 and are elastically pressed against the upper side of the master elements 2. The coupling sections 9 thus ensure particularly homogeneous and gap-free optical contact between the master elements 2, the composite web 3, and the coupling elements 8. The exposure module is not shown in this figure, but can be configured in various ways, including one or more light sources, mirrors, lenses, color filters, axes, and motors. Fig. 6D shows the positions of various elements of the preferred device after the exposure process. The coupling elements 8 begin to be raised back to their first height. At the same time, the laminating roller 7 begins to roll horizontally downstream. Fig.10 shows the coupling elements 8 and the laminating roller 7 in intermediate positions as they are moved after exposure.

[0215] Figure 6E shows the device 1 during a detachment step, in which the composite web 3 is detached from the upper side of the master elements 2. For this purpose, the laminating roller 7 is moved horizontally to the right. Preferably, a detachment roller located in front of the master elements 2 (not shown) can be lifted upward. The composite web 3 is arranged over the detachment roller so that it is also lifted by the lifting of the detachment roller.

[0216] Fig. 6F shows device 1 after the detachment step. The coupling elements 8 have been fully raised to their first height, and the composite web 3 has been detached from the master elements 2. A sufficient distance remains between the raised composite web 3 and the master elements 2 so that they can be removed, replaced, or rearranged without touching the composite web 3. Furthermore, the laminating roller 7 can be raised back to its first height at this stage. As a result, the composite web 3 is no longer clamped between the laminating roller 7 and the first carrier means 10. At this stage, the composite web 3 can continue to flow to later work stations of the process, for example, to a fixing module. The flow of the composite web 3 is preferably effected by a transport roller (not shown).

[0217] The following figures illustrate various exemplary exposure techniques and hologram types that can be produced using the method according to the invention and with the aid of the device 1.

[0218] Fig. 7 is a schematic front view of an edge-lit reflection hologram 13. The edge-lit reflection hologram 13 is located on a substrate body 14 and is enclosed under a cover 21. The reflection hologram 13, the substrate body 14 and the cover 21 form a master element 2. The arrows represent light rays for the reconstruction of a holographic image from the reflection hologram 13. During reconstruction, a reconstruction beam 19 is directed obliquely upwards onto a side surface of the master element so that the beam is reflected at a suitable angle to the reflection hologram 13. The beam 19 is refracted by the transparent substrate body 14 of the master element 2. The refracted beam passes through the reflection hologram 13, which is located in the master element 2, and is reflected back to the reflection hologram 13 at an upper boundary surface of the cover 21.Reference number 15 schematically shows the total internal reflection caused by the interface. The angle at which these totally reflected rays strike the reflection hologram 13 is crucial for its reconstruction. The totally reflected rays are reflected by the reflection hologram 13, which is represented by the dashed arrows. The resulting holographic image is thus essentially orthogonal to the surface of the hologram 13, which facilitates readability when placed, for example, on a vertical surface. The illumination is referred to as edge-lit because the reconstruction beam essentially strikes the hologram or substrate body 14 from the side.

[0219] Such a hologram can be advantageously used in glass panes illuminated from a side edge, so that the light source remains compact and concealed. The holographic image is essentially only visible when the light source, such as an LED, is activated from the appropriate angle, for example, to display a warning symbol on a windshield.

[0220] The edge-lit reflection hologram 13 can function as a master hologram. In order for the replicated holograms to also produce holographic images visible from the desired angle, the master hologram and the light-sensitive composite web must be exposed from an appropriate angle during duplication. This can be achieved using embodiments of the device and the method according to the invention, as explained below.

[0221] Fig. 8 is a schematic front view of a reconstruction of an edge-lit transmission hologram 16. The edge-lit transmission hologram 16 is also located on a substrate body 14 and is enclosed under a cover 21. The transmission hologram 16, the substrate body 14 and the cover 21 form a master element 2. During reconstruction, a reconstruction beam 19 is directed obliquely upwards onto a side surface of the master element 2 so that the beam strikes the transmission hologram 16 at a suitable angle. The beam 19 is refracted by the transparent substrate body 14 of the master element 2 and strikes the transmission hologram 16 at this angle. As it passes through the transmission hologram 16, the reconstruction beam 19 is at least partially diffracted by the edge-lit transmission hologram 16 to generate a holographic image.

[0222] In this example, too, the beams 12 for forming the holographic image are substantially orthogonal to the surface of the hologram. This can facilitate viewing, depending on the hologram's position relative to the user's eye level. This edge-lit transmission hologram 16 can also be used as a master hologram 6 to replicate the edge-lit transmission hologram 16 into a light-sensitive composite sheet 3. To ensure the desired reconstruction angle, the master hologram 6 and the composite sheet 3 must be exposed at exactly the same angle as the reconstruction beam 19 strikes the edge-lit transmission hologram 16 in Fig. 8.

[0223] Particularly with edge-lit holograms, as illustrated in the examples of Fig. 7 and Fig. 8, the necessary angle at which a reconstruction light must strike the replicated hologram in order to be correctly reflected and / or diffracted can be acute. Direct exposure at such an acute angle can encounter mechanical challenges. The use of the substrate body 14 increases the flexibility with which the light source can be positioned and moved for exposure. This is because the angle of incidence of the light on the master hologram 6 depends not only on the position of the light source, but also on the refraction caused by the substrate body 14.

[0224] Fig. 9 is a schematic front view of an exposure process for replicating an edge-lit reflection hologram 13 using a coupling element 8. A reference beam 11 is directed obliquely downwards onto a side surface of the coupling element 8, which is shown as a block above the master element 2. The reference beam 11 is refracted by the coupling element 8, and the refracted reference beam 11 passes through the composite path 3 to the master hologram 6. The refraction caused by the coupling element 8 contributes to achieving the acute angle of incidence required for the edge-lit hologram. The master hologram 6 reflects the reference beam 11, so that an object beam 22 (in the same direction as the reconstructed beam 12 from Fig. 7) passes from the master hologram 6 through the composite path 3.The object beam 22 interferes with the reference beam 11 in the light-sensitive material of the composite web 3 to generate the reflection hologram. These two beams impinge on the light-sensitive material from different sides, so the replicated hologram is a reflection hologram. Reference numeral 17 schematically indicates the two interfering beams.

[0225] A reconstruction beam 19 can be used to display the reflection hologram. The reconstruction beam 19 is reflected by the microstructure of the exposed photosensitive material in the direction of the dashed line designated by reference numeral 12, as explained in more detail for Fig. 7.

[0226] Fig. 10 is a schematic frontal view of an exposure process for replicating an edge-lit transmission hologram 16 using a coupling element 8. A reference beam 11 is incident on a side surface of a master element in an oblique upward direction. The reference beam 11 is refracted by the substrate body 14 of the master element 2, and the refracted beam is transmitted through the master hologram 6 and through the composite web 3. The reference beam 11 is transmitted through the master hologram 6 partially undiffracted and partially diffracted to generate an object beam 22, which also passes through the composite web 3. Due to the optical contact between the coupling element 8, the composite web 3, and the master element 2, there is essentially no interface between these elements at which the refractive index changes significantly. Therefore, unwanted reflections at the interfaces, which could interfere with the exposure, are avoided.This optical contact is also achieved by laminating the composite sheet 3 to the master element 2, the optional use of optical fluids and by the appropriate selection of materials with similar refractive indices.

[0227] The diffracted object beam 22 and the undiffracted transmitted reference beam 11 interfere in the light-sensitive material of the composite web 3 to inscribe the transmission hologram. The two interfering beams are identified by reference numeral 17. The two beams thus impinge on the light-sensitive material from the same side or in the same beam direction to replicate a transmission hologram in the composite web 3. A reconstruction beam that impinges on the composite web from the same angle as the diffracted reference beam 11 can be used to reconstruct the hologram. The reconstructed beam is schematically indicated by the dashed arrows 12.

[0228] Fig. 11 is a schematic front view of an exposure process for replicating a reflection hologram. In this embodiment, no coupling element 8 is used. The top side of the master element 2 is optically accessible during exposure. A reference beam 11 falls obliquely downward onto the composite web 3 and is refracted by the composite web 3 and / or cover 21, so that it is transmitted to the master hologram 6 at a suitable angle. The master hologram 6 reflects the reference beam 11 to an object beam 22, which traverses the composite web upward in the direction of the dashed arrow. Since the object beam 22 and the reference beam 11 strike the light-sensitive material of the composite web 3 from different sides or at different beam directions, the replicated hologram is a reflection hologram.

[0229] Fig. 12 is a schematic front view of an exposure process in which a multiplex hologram is replicated. The master hologram 6 comprises both a reflection hologram and an edge-lit transmission hologram, which can be replicated in the composite web. The transmission hologram is generated in a similar manner as explained above for Fig. 10. To generate the reflection hologram, another reference beam 11 is directed obliquely onto an upper surface of the coupling element 8. This is refracted by the coupling element 8 and transmitted through the composite web 3 to the master hologram 6. The master hologram 6 reflects the reference beam 11 to generate an object beam 22, which is transmitted upward through the composite web 3.The dotted-dashed arrows 22 show the reflected object rays of the reflection hologram, which interfere with the reference beam 11 to generate a reflection hologram in the light-sensitive material of the composite web 3. The dashed arrows 22 pointing upward, on the other hand, show the diffracted object rays of the transmission hologram, which interfere with the undiffracted portion of the reference beam 11 incident obliquely from below to generate an edge-lit transmission hologram 16 in the composite web 3.

[0230] With this arrangement, it may be advantageous to expose the transmission and reflection holograms separately. The coupling element 8 can be brought into contact with the composite web 3 during the exposure of the transmission hologram 16, while it is removed during the exposure of the reflection hologram. In such a case, the reference beam 11 used to write the reflection hologram is not refracted by the coupling element 8, as indicated by the dashed arrows 11. This can be taken into account when adjusting the angle of the light source so that the desired reconstruction signal of the hologram can be generated.

[0231] Fig. 13 is a schematic frontal view of an exposure process in which a transmission hologram 16 is exposed from below. In this example, one of the at least two optically accessible surfaces of the master element is the lower surface. The height of the master element 2 or the substrate body 14 can be advantageously used to refract the light of a reference beam 11 and ensure the desired angle of incidence of the light. This allows coupling through a polished underside.

[0232] Fig. 14 is a schematic front view of an exposure process for replicating a multiplex hologram comprising a transmission hologram 18 and an edge-lit reflection hologram 13. The transmission hologram 16 is replicated in a similar manner as explained above for Fig. 13. The light source is aligned below the master element 2 such that a reference beam 11 is directed obliquely upwards. The reflection hologram 13 is replicated by an edge-lit method with the aid of a coupling element 8, as explained above for Fig. 9. In this embodiment, the angles of the reference beams 11 used to generate the transmission and reflection holograms are selected such that the optical signal generated by the reconstruction of both holograms travels in the same direction, as represented by the two types of dashed arrows.

[0233] Fig. 15 is a schematic front view of an exposure process in which two edge-lit transmission holograms 16 are exposed simultaneously from both sides of a first carrier 10 having two rows. In this example, the first carrier 10 is configured to comprise two rows of master elements 2. The two rows are separated by a light-absorbing spacer 4. Furthermore, the coupling elements 8 in the second carrier are separated by an analogous light-absorbing spacer 4. The spacers 4 keep a buffer in the composite web 3 free from exposure. Furthermore, the composite web 3 can be exposed simultaneously from two directions, as shown in the figure. This increases the speed of the process. In this exemplary embodiment, the exposure process replicates a transmission hologram 16 on both shown master elements 2 in a composite web 3.However, it is quite possible that each master hologram 6 is exposed from a different angle and / or produces a different type of hologram. Thanks to the light-absorbing spacer 4, the reference beam 11 used to expose a master hologram 2 does not penetrate the neighboring hologram. This prevents interference such as crosstalk and increases the quality of the produced holograms.

[0234] Figures 16A-16F schematically show an embodiment of the invention, wherein the coupling element 8 is slid over the surface of the composite web 3 with an optical fluid 29. In this embodiment, the coupling element 8 has a prismatic shape with a trapezoidal cross-section, wherein the shortest side of the trapezoid corresponds to a contact surface 30 designed for contact with the master elements 2. The shape of the coupling element 8 can therefore also be referred to as a wedge shape.

[0235] Fig. 16A shows a first phase of the method. The master elements 2 are provided in a first carrier 10 such that their surfaces are substantially flush. A composite web 3 is provided for replication of the master elements. The composite web 3 is laminated to the flush surfaces of the master elements 2 using a laminating roller 7. For this purpose, the laminating roller 7 is moved from a storage position onto the surface of the master elements 2 so that the composite web 3 is located between the laminating roller 7 and the master elements 2.

[0236] When positioning the laminating roller 7 onto the master elements 2 prior to lamination, the laminating roller 7 can be moved, in particular rolled, along a plane comprising the surface of the master elements 2. Optionally, the laminating roller 7 is also lowered downwards to the level of the surfaces of the master elements 2. For this purpose, means for adjusting the height of the laminating roller 7 are preferably used. In order to compensate for variations between the heights of the master elements 2 and / or variations in the positioning of the first carrier means 10, it may be preferable to also adjust the height of the laminating roller 7. For this purpose, the laminating roller 7 can be lowered in steps of, for example, 50 μm until a desired pressure between the laminating roller 7 and the master elements 2 is reached. The reaching of the desired pressure can be detected by a suitable sensor. After the pressure orAfter positioning and adjusting the lamination roller 7, it is rolled over the surface of the master elements 2 to bring the composite web 3 into mechanical and optical contact with the master elements 2 without gaps and bubbles. The rolling of the lamination roller 7 is indicated by a horizontal arrow pointing to the left.

[0237] Fig. 16B shows a further phase of the process after lamination of the composite web 3 to the surface of the master elements 2. A dosing unit 28 for dosing optical fluid 29 is applied to the surface of a master element 2 at the end of the first carrier means 10. For this purpose, the dosing unit 28 is lowered from a storage position. The dosing unit 28 applies a quantity of optical fluid 29 to the master element 2, wherein the quantity of optical fluid 29 is designed to cover a contact area between the coupling element and the composite web. The dosing unit 28 is then returned to its storage position, as shown in Fig. 16C.

[0238] Fig. 16D schematically shows, with the downward-pointing arrow, the height adjustment of the coupling element 8 in order to bring the coupling element 8 from a storage position to a position close to the master elements 2. Fig. 16E shows the coupling element 8 after it has been positioned on the surface of a master element 2. Here, the coupling element 8 is in contact with the composite sheet 3, which in turn is laminated to the surface of the master elements 2. The contact surface 30 of the coupling element 8 is applied to the composite sheet 3 so that the optical fluid 29 is located between the coupling element 8 and the composite sheet 3. The optical fluid 29 crosslinks with both the contact surface 30 and the composite sheet 3 due to capillary forces. The optical fluid 29 thus completely excludes the gap between the contact surface 30 and the composite sheet 3.Since the optical fluid 29 has a refractive index that is essentially identical to the refractive index of the coupling element 8 and / or an upper carrier film of the composite web 3, it prevents unwanted reflections at interfaces between the contact surface 30 and the composite web 3. Furthermore, the optical fluid 29 can act as a lubricant, which supports the sliding of the coupling element 8 over the surface of the master element 2. The capillary forces cause the optical fluid 29 to inevitably follow the contact surface 30 as it moves along the surfaces of the master elements 2. This is schematically illustrated in Fig. 16F.

[0239] While the coupling element 8 is moving over the surface of the master elements 2, exposure occurs synchronously. For this purpose, a scanning reference beam 11 is directed onto the coupling element 8 such that it is bent into the desired exposure angle by the wedge shape. The scanning reference beam 11 follows the movement of the coupling element 8, e.g., by a laser itself being moved along a track together with a scanning unit. This is shown schematically in Figures 16E and 16F. After exposure, the coupling element 8 is removed from the master elements 2 (not shown). To overcome the capillary forces and avoid deformation or distortion of the composite track, the coupling element 8 is preferably moved laterally / longitudinally and upwardly in a continuous movement. Any suction effect is advantageously avoided or reduced.

[0240] Figures 17A-17E show an exemplary embodiment of the invention, wherein the coupling element 8 has a cylindrical shape. Analogous to the embodiment of Figures 16A-16E, an optical fluid 29 is introduced to improve the optical contact between the coupling element 8 and the composite web 3.

[0241] Fig. 17A shows a lamination step, wherein a lamination roller 7 is brought onto the surface of the composite web 3 so that the composite web 3 is enclosed between the lamination roller 7 and the first carrier means 10 or the master elements 2. The lamination roller 7 rolls over the surfaces of the master elements 2 to bring the composite web 3 into mechanical and optical contact with them. Figures 17B and 17C show the application of a quantity of optical fluid 29 to the composite web 3. This is done—analogously to the embodiment of Figs. 16A-16E—by means of a height-adjustable dosing unit 28. During these steps, the cylindrical coupling element 8 remains in a storage position, which in this embodiment is located above the plane of the laminated composite web 3.

[0242] The cylindrical coupling element 8 is then positioned from the storage position onto the accessible surface of the composite web 3, so that the composite web 3 is located between the coupling element 8 and the first support means 10 or a master element 2. In this case, this positioning of the coupling element 8 comprises a downward movement, which is enabled by the height-adjustable mounting of the coupling element 8. The downward movement is schematically illustrated by the downward-pointing arrow in Fig. 17D.

[0243] Fig. 17E shows the coupling element 8 after it has been positioned on the master elements 2. The figure also shows the initiation of a rolling movement of the coupling element 8 over the master elements 2. The contact surface 30 of the coupling element 8 is applied to the composite web 3 so that the optical fluid 29 is located between the coupling element 8 and the composite web 3. The optical fluid 29 crosslinks both the contact surface 30 and the composite web 3 due to capillary forces. The optical fluid 29 thus completely excludes the gap between the contact surface 30 and the composite web 3. Since the optical fluid 29 has a refractive index that is essentially identical to the refractive index of the coupling element 8 and / or an upper carrier film of the composite web 3, it prevents unwanted reflections at interfaces between the contact surface 30 and the composite web 3.

[0244] Since the cylindrical coupling element 8 contacts the composite web 3 only along a thin line or axis, the contact area 30 between the cylindrical coupling element 8 and the composite web 3 is smaller than the contact area 30 between the wedge-shaped coupling element 8 and the composite web 3. A smaller amount of the optical fluid 29 is therefore sufficient to bridge the interface between the cylindrical coupling element 8 and the composite web 3. Due to capillary forces, the optical fluid 29 remains between the composite web 3 and the cylindrical coupling element 8 during its movement over the surfaces of the master elements 2. This is schematically illustrated in Fig. 17F.

[0245] At the same time, a scanning reference beam 11 is directed onto the coupling element 8 in synchronization with its movement. The scanning reference beam 11 follows the movement of the rolling coupling element 8, e.g., by moving a laser itself along a track together with a scanning unit. This is shown schematically in Figures 17E and 17F.

[0246] List of reference symbols

[0247] F1 First side surface of a master element

[0248] F2 Second side surface of a master element

[0249] F3 Top surface of a master element

[0250] F4 Second side surface of a coupling element

[0251] F5 First side surface of a coupling element

[0252] 1 device

[0253] 2 Master element

[0254] 3 Composite railway

[0255] 4 spacers

[0256] 5 Absorber layer

[0257] 6 Master hologram

[0258] 7 Laminating roller

[0259] 8 Coupling element

[0260] 9 Coupling section

[0261] 10 First carrier medium

[0262] 11 Reference beam

[0263] 12 Reconstructed signal / object wave

[0264] 13 Reflection Edgelite HOE

[0265] 14 substrate bodies

[0266] 15 Totally reflected beam

[0267] 16 T ransmissions-Egelit-HOE

[0268] 17 Interference between reference and object beam

[0269] 18 T ransmissions-HOE

[0270] 19 Reconstruction beam

[0271] 20 repeat length

[0272] 21 Cover

[0273] 22 Object beam

[0274] 28 Dosing unit for optical fluid

[0275] 29 Optical Fluid

[0276] 30 Contact surface of the coupling element

Claims

PATENT CLAIMS 1 . Method for the replication of a plurality of holograms comprising the following steps: a. Providing a plurality of master elements (2) comprising a substrate body (14) and at least one master hologram (6), b. Selecting a sequence of master elements (2) from the plurality of master elements (2) depending on the plurality of holograms to be replicated and arranging the sequence of master elements on a first carrier means (10) such that upper surfaces (F3) of the master elements are aligned in a horizontal plane, c. Detachably laminating a photosensitive composite web (3) onto the aligned surfaces of the master elements (2), d. Exposing the master elements (2) to replicate the master holograms (6) in the photosensitive composite web (3), and e.Detaching the exposed composite web (3) from the master elements (2), characterized in that the master elements (2) are releasably inserted into the first carrier means (10) so that a sequence and / or composition of the master elements (2) for the replication of the plurality of holograms can be varied, and wherein the master elements (2) are inserted into the first carrier means (10) such that two or more surfaces of the master elements (2) are optically accessible for the purpose of exposure.

2. Method according to claim 1, characterized in that the master elements in the first carrier means (10) are separated along a linear arrangement, wherein the master elements (2) are preferably separated by light-absorbing spacers (4) and / or wherein a light-absorbing layer (5) is applied to vertical surfaces of the mast elements (2).

3. Method according to one of the preceding claims, characterized in that the method further comprises the arrangement of one or more optically transparent coupling elements (8) on the laminated composite web (3) so that a partial section of the composite web (3) is enclosed between the one or more coupling elements (8) and the master elements (2) during exposure.

4. Method according to the preceding claim, characterized in that the coupling elements (8) are arranged on a height-adjustable second support means, wherein a lower surface of the coupling elements (8) is preferably formed by a deformable transparent coupling section (9).

5. Method according to one of the preceding claims 3 - 4, characterized in that each master element (2) is assigned a respective coupling element (8), wherein preferably at least one lower surface of the respective coupling element (8) is congruent to an upper surface (F3) of the corresponding master element (2).

6. Method according to one of the preceding claims, characterized in that the substrate bodies (14) of the master elements (2) are of the same dimensions and preferably have a cuboid shape, wherein the substrate bodies (14) preferably have a height between 1 - 10 cm, a length between 3 - 20 cm and a width between 3 - 20 cm.

7. Method according to one of the preceding claims, characterized in that the at least two optically accessible surfaces of the master elements (2) are polished, wherein the degree of polishing is preferably at least P3, wherein the optically accessible surfaces preferably have an anti-reflective coating.

8. Method according to one or more of the preceding claims, characterized in that the substrate bodies (14) of the master elements (2) are formed from a material which is an optical plastic, preferably selected from a group comprising polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin polymers (COP), cycloolefin copolymers (COC) and / or an optical glass, preferably selected from the group comprising borosilicate glass, quartz glass, B270, N-BK7, N-SF2, P-SF68, P-SK57Q1, P-SK58A and / or P-BK7.

9. Method according to one of the preceding claims characterized in that a selection and optionally the arrangement of the sequence of master elements (2) is controlled by a control unit, wherein the control unit comprises a processor and a memory, wherein the processor reads sequence data from the memory and signals to an actuator and / or a user by means of an interface in which sequence the master elements (2) are to be arranged.

10. Method according to the preceding claim, characterized in that exposure instructions for the sequence are stored in the memory, wherein the processor signals a user and / or an actuator to adjust the position, path and / or wavelength of a light source according to the exposure instructions.

11. Method according to one of the preceding claims 9 - 10, characterized in that the control unit is connected to a sensor, wherein the sensor reads an ID feature of the individual master elements (2) or a storage location of the master elements and transmits the ID to the control unit for controlling and / or monitoring the sequential arrangement.

12. Method according to one of the preceding claims, characterized in that the method comprises an arrangement of the master elements (2) in two parallel rows, wherein the rows of master elements (2) are preferably separated by a light-absorbing spacer (4), wherein the spacer (4) is preferably part of the first carrier means (10).

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