EP4569381A1 - Method for replicating a plurality of holograms by means of a typecase principle - Google Patents

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

METHOD FOR REPLICATION OF A PLURALITY OF HOLOGRAMS USING A BOX PRINCIPLE

DESCRIPTION

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, so on that upper surfaces of the master elements are aligned in a horizontal plane, releasable lamination of a light-sensitive composite web onto the aligned surfaces of the master elements, exposure of the master elements in order to replicate the master holograms into the light-sensitive composite web, and detachment of the exposed composite web from the master elements, the master elements are releasably introduced into the first carrier means, so 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 introduced into the first carrier means in such a way that two or more surfaces of the master elements are optically visible for the purpose of exposure are accessible.

Background and state of the art

The invention relates to the field of replication of holograms.

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

Such holographic elements are used in many areas, such as: B. in transparent displays (e.g. in shop windows, refrigerated cabinets, vehicle windows), for lighting applications, such as information or warning signals in glass surfaces, 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, for example covering 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 allows the production of holograms from a computer-generated image and is considered particularly suitable for the production of one-off versions of holograms, customized holograms, or for the production of master holograms that are later duplicated. An exemplary process of this type 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 cost-intensive, making it uneconomical to use, especially with very large master holograms.

Commercially available HOEs, on the other hand, are often mass-produced through duplication processes. Such reproduction processes usually use a master hologram, which has 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 because the master holograms are typically made of a more durable metal or are embedded in a transparent substrate of high rigidity and surface quality as a master element. The production of master holograms is also costly due to the use of custom processes, whether traditional or computer-generated.

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 may be horizontally oriented. The combination of the master hologram with the substrate body forms a master element. The size of the master element is usually a multiple of the size of the master hologram. The heavy weight of master elements is caused by the hard, transparent materials such as glass used for the substrate body.

The continuous duplication of a single master hologram to produce a series of identical copies of such HOEs is known. Typically, this process occurs through an embossing process into a light-sensitive material to produce reflection holograms. The reproduction can also be done by optical exposure to create a volume hologram. In these cases, a light-sensitive Material brought into optical contact with a master element and exposed to coherent light. To enable continuous processing and increase the speed of the process, the photosensitive material may be provided in the form of a web and transported by rolling through various work stations to produce the HOEs. Such tracks are often only available in standard widths, which are adapted, for example, to the width of rolls in the workstations.

Especially in the case of small HOEs (width or length <150 mm), their replication on such a path with a single master element often cannot be carried out in a process- or material-efficient manner. Especially in cases where the width of the web is many times greater than the width of the HOE, a large part of the light-sensitive web must be cut away and disposed of in later work steps. This leads to material waste, higher costs and also limits the speed and efficiency of the copying process.

An alternative may be to use multiple master holograms to produce the HOEs side by side across the width of the web. Although this improves material utilization, it creates challenges for the placement of the master holograms. In particular, unevenness between the master holograms can lead to poor optical contact between the web and the master holograms, so that undesirable reflections occur at the interfaces. A possible solution to this problem is to integrate different master holograms into a single, large-area master element. A large-area master element can provide a perfectly flat and continuous surface to create the required optical contact with the web.

However, the production of large master elements with a large number of master holograms is expensive, among other things because the production of large-area optically flawlessly polished substrates is not trivial. In addition, such master elements are more difficult to move due to their weight, which makes it difficult to insert and remove such large master elements from a production line. In addition, the storage and logistical provision of a large number of heavy and cost-intensive master elements is not very practical.

In addition, when positioning master holograms in a space-efficient manner, undesirable optical interference can occur in the HOE generated. For example, reference beams used to expose a master hologram may propagate or be scattered and reach a neighboring hologram, causing that too to be inadvertently exposed. To avoid this, large buffer distances between the master holograms are required, which has a disadvantageous effect on the material-efficient use of the master elements as well as the light-sensitive path. Identical master holograms can be present on a master element in order 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.

However, it can also be preferred that master holograms of different motifs should be replicated at the same time. On the one hand, this can be preferred in order to use one replication system for different applications at the same time. To provide a large-scale HOE, it may also be necessary to replicate a large number of HOEs of different types, which are then combined to form a large-scale HOE.

The different holograms to be replicated can differ from each other not only because of the motifs they contain, but also because of 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 need to be exposed in different ways and from different angles, for example to match the position of a light source used to reconstruct the hologram. In order to reduce the effort, it would also be advantageous if different types of master holograms with different motifs as well as different exposure methods could be exposed on a path in a single device.

In the event that the same master element includes a large number of master holograms of different motifs and types, simple laser scanning over the entire master element is not suitable. The design of an optical setup in order to expose different master holograms of the same master element from different angles without areas being exposed incorrectly is complex. In addition, in this case, the master holograms in the master element must be separated from one another particularly widely in order to avoid unwanted superimposition of light beams.

A further problem arises if one or more master holograms in the master element prove to be faulty, degraded or should be changed. Since the master holograms are firmly connected to the substrate body, they cannot be replaced individually without replacing the entire master element.

In particular, if changes are only required in a portion 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. However, as explained above, this is uneconomical for most commercial applications. There is therefore a need to provide a more efficient method for reproducing holograms, which allows changes in a simple manner and is particularly suitable for 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.

For many applications, e.g. B. for the production of personalized security features (e.g. a holographic date of birth, a holographic date of issue, a holographic serial number or similar), the known methods of serial reproduction are not easily suitable. This is because the hologram being created can either be unique or contain a unique combination of features such as numbers, symbols and images. In addition, these holograms may be required to be of different types with different exposure requirements. For example, transmission holograms may be necessary for use in glasses with a certain tint or strength (see WO2016202595A1). It may also be necessary for the holograms to be reflection holograms, for example for use in a display. The holograms may need to be a certain color or only be visible from a certain angle.

From US2007024939A1 a method is known that increases the flexibility of using master holograms in a production series. The method involves bringing a photosensitive web into contact with a matrix of small, discrete master elements. The master elements themselves include changeable features such as: B. a counter and are arranged in a framework so that only their top is accessible for exposure. The arrangement therefore enables exposure from only one side in order to produce reflection holograms only.

Furthermore, the arrangement known from US2007024939A1 does not offer precise guidance of the exposure light to the master elements or the light-sensitive path. The angles from which the light incident through the photosensitive track can reach the master elements are limited because 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 production run, they must all be copied in the same way to form reflection holograms only. The master holograms stand in front of a mirrored background. Furthermore, there is no provision for protecting adjacent copies from interference from light reflected from adjacent master holograms. Exposing the master holograms from above is revealed to be the only way to create different holograms in the light-sensitive path without causing unwanted superimpositions between the different images. During exposure as described in this document, the reference beam must pass through various components with different optical indices through which it is refracted differently. Between layers with different optical indexes - for example between the master elements, the light-sensitive web and the surrounding air - interfaces occur at which there is a high risk of reflections. This can cause undesirable exposure patterns to occur.

From DE 10 2010 2014 3015 A1 a method for replicating multiple reflection holograms is known. The holograms to be copied are provided side by side on the surface of a drum with a polygonal cross-section or prismatic shape, each lateral surface of the drum having at least one master hologram. A photosensitive material is passed over the surface of the drum for exposure. To eliminate air gaps, particularly at the corners of the drum, between the photosensitive material and the drum, rollers are passed over the surface of the drum. Similar to the device according to US2007024939A1, this arrangement only allows exposure of reflection holograms. There is no greater flexibility in exposing different types of holograms. Additionally, wrapping the photosensitive material over the surface of a multi-sided prismatic drum can degrade the mechanical quality of the photosensitive material and leave undesirable grooves or wrinkles. An arrangement is therefore required that enables the gentle handling of a composite web in order to carry out a flexible replication process.

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

Task of the invention

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 which is suitable for material-saving replication of holograms with high precision and quality, preferably different holograms with different exposure requirements can also be replicated.

Summary of the invention

The task is solved by the features of the independent claim. Advantageous embodiments of the invention are described in the dependent claims.

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 so that upper surfaces of the master elements are aligned in a horizontal plane, c. Removable lamination of a light-sensitive composite web onto the aligned surfaces of the master elements, i.e. exposing the master elements to replicate the master holograms into the photosensitive composite web, and e. Detaching the exposed composite web from the master elements, wherein the master elements are releasably introduced into the first carrier means, so 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 introduced into 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.

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 there is 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 picture or appear as a standalone component. Additionally or alternatively, the master elements can represent individual holograms that are to be separated after copying. Using multiple smaller master elements to cover an area that would normally be covered by a single large master element can reduce the complexity of a system. Minor changes or defects to a master element do not require replacement of all elements. In addition, the master elements can be made smaller. This reduces the costs for producing and installing the master elements enormously. 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 systems often have a maximum size limit for the materials used. By limiting the dimensions of the master element, a high degree of polish can be ensured with 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 can be easily inserted into or removed from a replication device.

Furthermore, the method according to the invention allows optimal material utilization of the light-sensitive composite web. Preferably, the carrier means can extend over the entire width of the composite web, so that the master holograms can be replicated in areas of the composite web over its entire width. The provision of separate master elements in a carrier means advantageously also allows the individual master elements to be optically separated from one another in order to avoid scattered 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 means itself can provide light-absorbing spacers. The provision of separate master elements therefore allows a number of measures to enable significantly closer positioning of master holograms without compromising the precision or quality of replication.

In addition, by providing a large number of such master elements, a pool of different building blocks can be provided. By selecting master elements from such a variety, 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 produce a wide variety of images, patterns or text, while significantly reducing costs compared to digitally controlled single holography. Metaphorically speaking, an individual holography can be compared to writing by hand, while the selection of the master elements from the large number of master elements uses a more economical typesetting box principle analogous to a Gutenburg press. By selecting the master elements from the large number of master elements according to a sequence, individual holograms can only be produced in the number and order 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 inventive method to be integrated into 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 that of the automobile production sequence. This means that intermediate logistical steps can be eliminated, which increases efficiency. Since only the exact number of pieces required is produced, there is also less waste. For similar reasons, the method according to the invention is also suitable for high-security applications such as banknotes and identification documents.

Furthermore, the carrier means advantageously makes it possible to place the individual master elements in the device in such a way that they are at fixed, known distances from one another. This ensures very high precision in placement, which allows the replicated holograms to be separated if necessary later in the process. In a preferred embodiment of the invention, the master elements are present in a linear arrangement in the first carrier means.

The carrier means also allows the master elements to be placed so precisely that their surfaces are flush with each other and with the carrier means. This means that the large number of master elements can also be used with thin, flexible, light-sensitive materials without damaging them. This represents a departure from previous views, according to which the use of several master elements arranged next to one another in a single pass would result in edges or projections on a flowing composite web made of light-sensitive material leading to wear or damage.

Due to the aligned horizontal surface created by the combination of the master elements with the carrier medium, a photosensitive material can instead be laminated onto the master elements with high precision and with only low shear forces.

The lamination brings the light-sensitive material into mechanical contact with the master elements and ensures sufficient optical contact with the master holograms. By laminating instead of simply placing the light-sensitive material on the master elements, a particularly homogeneous contact can be created between the master element and the light-sensitive material, which effectively avoids bubbles or wrinkles. By using a composite web of the photosensitive material, this can be done repeatedly over the arrangement of the master elements in an efficient manner so that the composite web flows while the arrangement of the master elements preferably remains stationary. In particular, a removable lamination makes it possible to remove the composite web without damage or residue and to continue running it through further stations in a production line.

By constructing the support means such that at least two surfaces of each master element are kept optically accessible, the same pass of the method can include the exposure of both reflection and transmission holograms. For example, a first master element can be exposed from above onto its upper horizontal surface, so that the light falls through the light-sensitive composite web, is reflected by the master hologram and falls again through the light-sensitive composite web. This would create 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 light-sensitive composite web, creating a transmission hologram. The process thus allows greater flexibility in producing different holograms with different properties in one and the same run.

A “sequence” in the sense of the invention is preferably a sequence of several elements. The elements in the sequence can be identical and repeat or vary. The order is preferably predetermined.

An “arrangement” within the meaning of the invention is preferably a physical positioning of elements in predetermined positions, preferably according to a predetermined order. The arrangement of the master elements is preferably a linear arrangement.

A "linear arrangement" within the meaning of the invention is preferably a physical positioning of elements so that they form a line along one of their edges, along their center and/or another reference point. The “linear array” may preferably include multiple lines forming, for example, rows and columns.

A “support means” in the sense of the invention is preferably a means that holds several 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 brackets, where the brackets may relate to a common mechanical reference, such as a rail. Preferably, the carrier means includes gaps and/or recesses that are designed to precisely fit a master element.

A “lamination” or “lamination” in the sense of the invention is preferably a joining process between two components. The lamination is preferably designed so that the composite sheet continuously covers an area so that there are no gaps, bubbles or wrinkles. Lamination is preferably carried out using a lamination roller. The lamination is preferably carried out at room temperature, for example at a temperature of 20°C -25°C. However, the lamination roller can also optionally be heated to 20 - 300 °C, preferably 20 - 100 °C or 40 - 80 °C. The temperature of the lamination roller may preferably be adjusted so that the composite web is softened but does not melt. The lamination is preferably designed so that no permanent connection is created between the composite web and the master elements or the carrier means. The lamination can also be carried out with the aid of aids such as an adhesive, the adhesive preferably being so weak that the parts can be separated from one another with a force of less than 10 N, preferably less than 5 N. The adhesive is preferably easy to clean, e.g. B. through water solubility and leaves no residue on the composite membrane. More preferably, the adhesive evaporates without leaving any residue at room temperature.

A “composite” in the sense of the invention is preferably a multilayer material that consists of two or more different components with different physical properties that are connected to one another at an interface. Preferably, the bond between the individual components is such that it cannot be separated by minor force and is therefore considered permanent. The composite can, for example, consist 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 of which is light-sensitive to different spectral ranges.

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 wrapped around a roller. The composite web preferably has a thickness of up to 300 μm. The composite sheet includes a light-sensitive material. Preferably, the composite web encloses the photosensitive material between two transparent support films which have a similar refractive index to the photosensitive material. The refractive index of the carrier films and the light-sensitive material is preferably between 1.4 and 1.6. The light-sensitive material may be, for example, a light-sensitive photopolymer or a dichroic gelatin. The light-sensitive material can be light-sensitive or wavelength-selective for the entire visible spectrum.

In the context of the invention, “exposure” preferably means the targeted directing of electromagnetic rays onto a correspondingly sensitive surface to form a hologram. Various methods of exposing a hologram are known, including transmissive or reflective techniques for producing volume holograms. Examples of this are explained in more detail later in this text.

A “master element” is preferably a three-dimensional unit that includes a master hologram in a form that facilitates its handling and mobility. In particular, the master hologram is enclosed in a positionally fixed manner by the master element in such a way that a movement of the master element directly leads to a corresponding movement of the master hologram. Preferably, the master element has a length and width that approximately correspond to that of the master hologram. Preferably, the master element is 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 enables a mosaic or linear arrangement.

The master element comprises a substrate body that either encloses or supports the master hologram. For example, in embodiments, the master element may include a transparent top cover for protecting a master hologram present between the cover and the substrate body. Preferably, the top cover has a refractive index selected such that light is transmitted through it, the master hologram and the substrate body without being significantly reflected at the interfaces between the substrate body, master hologram or the cover. The top cover can be, for example, a transparent film or a glass layer. The materials of the substrate body, the master hologram and the cover are preferably selected so that the differences in refractive index between the individual layers are small. This allows internal reflections to be avoided.

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 along a composite sheet flow direction. Preferably, the “height” refers to a dimension in a vertical plane orthogonal to the plane formed by the latitude and longitude.

A “substrate body” in the sense 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 multiple surfaces, including a top surface that may be horizontally oriented.

For the purposes of the invention, the term “transparent” or “transparency” preferably refers to a property of a material whereby it is essentially transparent to light. Preferably, a transparent material in the sense of the invention is at least for a part of the electromagnetic spectrum, preferably with a wavelength between 100 nm - 1 mm, particularly preferably between 400 nm - 780 nm. Particularly preferred is a transparent material, for example a transparent substrate body, permeable to light in a wavelength range with which the master holograms are exposed. A transparent material can also be colored in such a way that it selects the light radiation of a specific wavelength.

A “master hologram” in the sense 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 a plurality of wavelengths. For this purpose, for example, several holograms, e.g. B. each diffract light of one wavelength and / or multiplex holograms that diffract light of several wavelengths are arranged as hologram stacks. The master hologram can be, for example, a diffractive optical element (DOE). Diffractive optical elements (DOEs) use a surface relief profile with a microstructure for their optical function. Alternatively, the microstructure may also be present in the volume of the element in the form of a local difference in refractive index. The light transmitted by a DOE can be converted into almost any desired distribution through diffraction and subsequent propagation. This can be an image, a logo, text, a light refraction pattern or similar. In addition, the master hologram can be a technical hologram, such as a Bragg mirror, a diffuser or a hologram functioning as a lens.

The process for producing the master hologram can 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 method, a first coherent beam, the object beam, is reflected from an object and onto a recording material that is simultaneously exposed to a second coherent beam, the reference beam. The object beam and the reference beam interfere and create an interference pattern on the recording material. This interference pattern or fringe pattern is recorded from 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 from 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 additional copies with the same image. The master hologram can preferably also be computer-generated. The microscopic gratings that produce the diffraction effects can e.g. B. can be produced by laser interference lithography. In this technique, two or more coherent light beams are configured to interfere on the surface of a recording material. The positions of the light beams in relation to the recording material can be controlled by a computer. Depending on the strength of the laser, the recording material can consist of almost any material. Other techniques such as electron beam lithography can also be used to digitally produce the master hologram. The master hologram may preferably comprise glass, silicon, quartz, UV varnish, a photopolymer composite and/or a metal such as nickel.

An “optically accessible area” within the meaning of the invention is an area 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 support means may cover part of the optically accessible surface. Preferably the frame covers no more than 50%, preferably no more than 40%, 30%, 20% or 10% of the optically accessible area. Preferably, an optically accessible surface is also not very reflective. It may be preferred that the optically accessible surface has a reflectance for visible light at 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 makes it possible to increase the utilization of the incident light for illuminating the composite web.

In a preferred embodiment of the invention, the master elements are present separately 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 affecting the replicated hologram. At the same time, the distance can make handling the replicated holograms easier. On the one hand, the separation of the respective holograms is easier. On the other hand, even after cutting it 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 quality is increased. The master elements are preferably separated by light-absorbing spacers. This protects the master holograms and the portion of the composite web lying thereon 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 to unwanted patterns that overlay the replicated image and reduce its quality. If a first master element is exposed by light directed onto its side surface without a light-absorbing barrier being present, the light can, for example, reach a second master element which is arranged in a row next to the first. In this way, the second master element can be exposed from an inappropriate angle, causing an unintentional ghost image on the relevant part of the composite web. This phenomenon is called “cross-talk” and is particularly effectively prevented by using light-absorbing spacers.

By integrating the light-absorbing spacer into the carrier means, the outward-facing side surfaces and the top 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 in order to enable exposure from different orientations, for example for transmission or reflection, possibly in an edge-lit or back-lit configuration.

Alternatively or additionally, it may be preferred 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 support medium. This means that several master elements can be exposed next to each other without causing optical interference, while at the same time maintaining a minimal buffer distance or an almost continuous effect in a replicated hologram made up of several components of the different master holograms.

This advantageously enables an almost seamlessly replicated (overall) hologram with large dimensions and high image quality without having to use an equally large master element. In addition, small changes can be made to part of the hologram without having to replace all master elements. An area of a (overall) hologram to be replicated, which is to be changed between runs, can, for example, concern the (national) language of a text element that is used in a head-up display in a car. As a further example, the necessary arrangement or orientation of the master elements may also vary depending on whether it is a head-up display for a left-hand drive or a right-hand drive vehicle of the same model. The method according to the invention using a case principle which allows individual master elements to be easily replaced accordingly, allowing such adjustments to be implemented quickly and cost-effectively.

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

Preferably, the first carrier means is mounted so that it can be tilted and/or adjusted in height, the device for replicating the master holograms preferably comprising means for adjusting an angle of inclination and/or height adjustment of the first carrier means. For the purposes of the invention, such means can also be referred to as an alignment unit for the first carrier means and are known to those skilled in the art. Exemplary means for setting a height adjustment of the first support means include an adjustment table with actuators for up and down movement. The first carrier means and the master elements contained therein can thus be brought into contact with a further process component, in particular a composite web, an optical adhesive film, a laminating roller and/or one or more coupling elements.

Means for adjusting an angle of inclination can preferably also include 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 can advantageously ensure a particularly plane-parallel alignment of the master elements, which are located within the first carrier means, to the composite web or to coupling elements (described further below). The rotation of the entire first carrier means allows a uniform alignment of the master elements.

The means for setting 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°.

Alternatively or additionally, the further process components are mounted in a height-adjustable manner in order to establish sufficient contact between the process components to carry out the replication method. Other process components may include: transport rollers or transport components for positioning the composite web, any coupling elements, a laminating roller, a metering unit for applying an optical liquid 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 enable fine adjustment of your positions with a height adjustment accuracy of at least 10 pm, preferably at least 5 pm.

In a preferred embodiment, the first carrier means is spring-mounted. The suspension can be designed to be active or passive and is preferably designed to tolerate an up and down movement of the first support means. The suspension is preferably carried out mechanically, (electro-)magnetically, hydraulically or pneumatically, with pneumatic suspension being particularly preferred. Preferably, the suspension is configured for a height adjustment of at least 20 pm, preferably at least 50 pm, particularly preferably at least 100 pm and/or at most 1000 pm, preferably at most 500 pm, particularly preferably at most 200 pm.

Preferably, the suspension of the first carrier means is pressure-controlled, in particular in order 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 at the same time compensating for any tolerances in the height of the surface of the master elements. Advantageously, by providing a spring-loaded first carrier means in the process of replication, any height differences between individual master elements that are located within the first carrier means can also be compensated for. An inclination of the first carrier means can also be compensated for. For example, as explained in more detail below, it may be preferred to use a laminating roll to apply a composite web to the master elements. For this purpose, the lamination roller preferably successively sweeps over the composite web and the underlying master elements, with optimal height and pressure conditions being set for each of the swept master elements by means of the spring-loaded mounting of the first carrier means. Due to the suspension, the first carrier means can also move slightly up and down synchronously with the lamination roller, for example, in order to compensate for differences in height between the master elements. This means that all master elements can be brought to exactly the required height.

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.

In a further preferred embodiment of the invention, the master elements can be positioned in the first carrier means in a spring-loaded manner. The first carrier means can therefore preferably also have means for individually suspending the master elements, in particular independently of one another. include. For example, a base of the first carrier means can be provided with an elastic material, for example a foam.

As a result, variations in the dimensions of the master elements within the first carrier means can be compensated for, so that, for example, the composite web can be clamped seamlessly between planar coupling elements and the master elements.

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

For the purposes of the invention, a "coupling element" is preferably a three-dimensional block of transparent material with a refractive index and dimensions that are configured to direct the exposure beams towards 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 different optically accessible surfaces. Preferably, at least one side surface or base surface and a bottom surface or lateral surface of the coupling element are optically accessible. Preferably, an optically accessible surface of the coupling element is also not very reflective. It may be preferred that the optically accessible surface has a reflectance for visible light at 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 makes it possible to increase the utilization of the incident light for illuminating the composite web.

With the coupling element, an exposure beam can be directed 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 it is reflected back by the composite web. The reflected light is directed by the coupling element in such a way that it does not hit adjacent parts of the composite web and its scattering is minimized. Alternatively, the light can also be passed through the master hologram to expose a transmission hologram in the composite web. The coupling element can also serve to hold the composite web over the surface of the master elements. Since the coupling element does not have to be exchanged between the series, a single plate can be used that covers all linearly arranged master elements in the carrier means. In this way, there is no risk that edges of the coupling elements could leave traces on the composite membrane. In addition, aligning the coupling element over the carrier means is simplified.

However, it may be preferred to use multiple coupling elements. This reduces the size and weight of each coupling element and makes storage and replacement easier. This also offers advantages in terms of the quality of the coupling elements, since polishing systems often have a maximum size limit for the materials used. A high degree of polish can be achieved by limiting the dimensions of the coupling element in this way.

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 the two elements to be assigned to one another with a precise fit and, insofar as the coupling elements would leave impressions or traces on the composite web, these would be 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 produced and stored more cost-effectively in larger quantities.

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 to an upper surface of the corresponding master element.

In a further preferred embodiment of the invention, the coupling elements are arranged on a height-adjustable second support means. The second carrier means can be configured analogously to the first carrier means. In particular, the second carrier means - analogous to preferred embodiments of the first carrier means - is mounted so that it can be tilted and/or adjusted in height. Likewise, suspension of the up and down movement of the second carrier means may be preferred. It may be preferred that the second carrier means 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 carrier means, the coupling elements can preferably be brought into contact with the composite web after lamination of the composite web and before its exposure.

It may be preferred that the lamination takes place in the same stretch 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). Lamination of the composite sheet may be accomplished by means of a roller which is lowered onto the composite sheet and rolls over the composite sheet to bring it into close contact with the aligned horizontal surface of the master elements. The laminating roller and/or the master elements can preferably be spring-mounted in order to maintain contact between the two components despite variations in the surface position or surface quality of the components. The laminating roller can then be raised or retracted so that the coupling elements can then be lowered to establish contact with the composite web (second height). In the position of the coupling elements, the composite web is therefore clamped between the coupling elements and the master elements.

The exposure can be carried out using both the master elements and the coupling elements. After the exposure has been completed, the coupling elements can be raised again to a first height position at a distance. Optional fixation can be done in place and the composite sheet can be detached from the surface of the master elements, e.g. B. by one or more other rollers lifting from below one or more parts of the composite web that lie outside the first carrier means for the master elements. The first carrier remains accessible so that the order of the master elements can be changed. In this way, multiple process steps can be carried out in a single area. This increases the compactness of the method and the device used for it.

In a preferred embodiment of the invention, the same coupling element is used for exposing different master elements. Here, 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 can be used in the form of a cuboid coupling plate, the length of which extends over all master elements. Alternatively, a coupling element can be moved over the surface of the master elements, with exposure preferably taking 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 so that only a limited area is always in contact with the composite web during exposure. This surface is preferably referred to as a “contact surface” in the sense of the invention. Particularly in the case of a coupling element which is designed to roll over the composite web, the contact surface of the coupling element can constantly shift while remaining the same size.

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 should preferably be avoided. Depending on the application, the use of curved or planar surfaces may be preferred, as explained below.

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. The cylindrical coupling element can thus establish optical contact along an axis with the composite web. Light from a lateral surface and/or a base surface can be directed onto the composite web and the master elements via the coupling element. Preferably, a light source and/or a light-deflecting component moves synchronously with the coupling element in order to expose the master elements.

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

In preferred embodiments of the invention, the cylindrical coupling element itself functions as a laminating roller or vice versa. The cylindrical coupling element can also improve mechanical contact between the composite web and the master elements. With this arrangement, lamination is preferably carried out synchronously with exposure. There is no need for a separate lamination roller. This is particularly space-saving and increases the throughput of the process. Another 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 liquid between the coupling element and the composite web. On the one hand, the amount of optical used can Fluid should be kept to a minimum. On the other hand, the forces required to remove the coupling element from the composite web are also reduced. The removal of the cylindrical coupling element can therefore be carried out in a particularly gentle manner for the composite web. This will be explained in more detail in relation to the use of optical fluids.

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. The weight of the coupling element can be kept low. The coupling element also has a narrow contact surface to the composite web, which is advantageous when using optical liquids. When exposing such a coupling element, a lens function should preferably be avoided.

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 web. Preferably, the cross section of the coupling element tapers to the planar contact surface, so that the prismatic shape can also be referred to as a wedge shape in the sense of the invention. For example, the coupling element or at least a section 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 web as a planar surface. By means of the embodiment, the contact surface between the coupling element and the composite web can be optimally adjusted, in particular also chosen to be larger than would be the case with a cylindrical coupling element, in which the contact surface essentially corresponds to a line, depending on the size of the curvature. Particularly when using an optical fluid, a larger contact area can be maintained smoothly and without gaps when the coupling element is displaced. Increased capillary forces between the contact element and the composite web advantageously prevent the formation of air gaps, so that particularly good optical contact occurs.

In a further preferred embodiment of the invention, the contact between the coupling element and the composite web occurs on the surface of the master elements with a predetermined pressure. For this purpose, compressive force sensors or pressure sensors are preferably provided for measuring a compressive force or a pressure between the coupling element and the master elements. A film coating can preferably be used as a sensor for the pressure exerted by one process component on another can be used, with a pressure sensor distributed over the entirety of a 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.

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 with respect to the master elements. Preferably, coupling elements with deformable coupling sections are neither rolled nor displaced over the surface of the composite web that is in contact with the master elements.

For the purposes of the invention, a “coupling section” is preferably a part of the coupling elements which consists of a transparent deformable material and is designed in such a way that it ensures 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%, more preferably +/-5% of the refractive index of the main body of the coupling element, the composite sheet, an upper cover of the master element, the Master hologram and/or the substrate body of the master element.

The deformability of the coupling section allows it to be pressed onto the composite web while the composite web is on the aligned surface of the master elements in such a way that no gaps or bubbles remain. This ensures particularly homogeneous optical contact between the three elements of the sandwich. Unwanted optical aberrations or patterns are avoided, giving the final product a higher quality.

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 particularly suitable as a material for achieving a sufficient refractive index and at the same time being sufficiently elastic, easy to clean and leaving no residue on the composite web. Additionally or alternatively, it may be preferred that an optical liquid 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 in order to ensure interference-free transmission of the light. The optical fluid can also improve the optical contact between the elements by compensating for any wedge errors, 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.

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

In a further preferred embodiment of the invention, the metering unit is mounted in a height-adjustable manner. 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 liquid and then removed to create space for further process components such as coupling elements or light sources.

In a further preferred embodiment of the invention, an optical liquid is introduced between the composite web and a coupling element. The amount of optical liquid used is preferably designed to cover a contact surface between the coupling element and the composite web. Preferably, the optical liquid adheres to the surfaces of the coupling element and the composite web by means of capillary forces. With larger contact surfaces between the coupling element and the composite web, larger forces are generated. This is advantageous in order to maintain optical contact during movement of the coupling element over the composite web.

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.

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 separated from the composite web by a vertical movement Will get removed. 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 already taking place. In this way, undesirable force transmission to the composite web can be effectively avoided. When using a coupling element with a curved contact surface - for example when using a cylindrical coupling element - such a movement for the removal of the coupling element can preferably be omitted, since the narrower contact surface reduces the risk of deformation or distortion of the composite web.

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 introduced between a master element and the composite web and/or between the composite web and a coupling element.

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.

Preferably, the materials used for the optical adhesive film have identical or similar optical properties to those materials used for the substrate of the master element (or the coupling element or its coupling section) and/or the composite web. Preferably, the similar or identical properties include transparency, haze, stress birefringence properties and/or refractive index. The use of identical or similar materials enables a very close adaptation of the refractive index of the optical adhesive film to the refractive indices of the adjacent process components, so that a transition between the adjacent refractive indices can be ensured without jumps in the refractive index. Reflections at the interface between the master element (or the coupling element), the optical adhesive film and/or the light-sensitive composite web will thereby be largely eliminated or significantly minimized.

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 sheet 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 sheet 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 more preferably not more than 0.05.

In a further preferred embodiment of the invention, a 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 light-sensitive 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 is preferably 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 trouble-free transition of light rays between the various process components with minimal reflections and/or aberrations at interfaces.

Furthermore, the optical adhesive film is preferably a solid in which the Brownian motion is sufficiently small, which prevents the phase of the light from “wobbling” and thus results in a more stable interference field in the hologram copy within the exposure time. In this way, the microstructures do not blur, which maximizes the diffraction efficiency of the holograms. The sharpness and contrast of the hologram created is 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.

The optical adhesive film can be shaped analogously to the composite web and moved through the process in an analogous manner, for example with the help of rollers. This enables 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 photosensitive 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 lamination of the composite web and the optical adhesive film.

In contrast to the OCAs (optical clearance adhesive) known from the field of optical displays, the optical adhesive film preferably has low adhesive strength in addition to its advantageous optical properties. This allows the optical adhesive film can be removed from a surface without leaving any residue and with little force after use.

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 light-sensitive composite web of less than 3 N/cm (Newton per centimeter), preferably less than 1 N/cm. In preferred embodiments, however, the peeling 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 light-sensitive 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, after a 180 degree peel test. In preferred forms, the measurement is carried out in accordance with ASTM D903.

In a preferred embodiment of the invention, the optical adhesive film has a single-layer layer structure, the layer structure having exactly one adhesive layer. The exactly one adhesive layer is preferably adhesive on both sides in order to provide optical contact.

In a preferred embodiment of the invention, the optical adhesive film comprises two adhesive layers, 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 at the same time, which means that particularly good optical contact can be achieved and the risk of air gaps or unwanted reflections is reduced.

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 winding roller for unwinding the optical adhesive film after use. The method preferably includes a step of removing the optical adhesive film from the relevant process component after exposure. Preferably, the device further comprises a lamination roller for the temporary lamination of the optical adhesive film on 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 may include take-up rolls for removing the protective layers prior to use of the optical adhesive film. In a further preferred embodiment of the invention, the first carrier means is designed so 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 carrier means can be arranged in a displaceable and/or clampable manner. The first carrier means can also be designed so that it can accommodate master elements of different thicknesses. To bring the tops of the master elements to the same level, filler substrate blocks can be placed under one or more master elements.

In a further preferred embodiment of the invention, the substrate bodies of the master elements have the same dimensions. The substrate bodies preferably have a cuboid shape. The use of identical square shapes for the master elements has proven to be particularly easy for the alignment of the master elements in the first carrier means. However, it is also possible to use different shapes, with the shapes or dimensions varying in particular 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 in view of less material use.

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.

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 area on the side of the master elements for exposure. The preferred heights also allow exposure from different angles to be carried out in a simple manner in order to meet different requirements for the replication of the holograms. 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, especially 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, the manufacturing costs can be reduced and particularly easy handling can be achieved for substrate bodies with a length and/or width of up to 20 cm.

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

If a surface of the coupling element is brought over the composite track against a surface of the master element, it is advantageous for both surfaces to be polished. It is also further preferred that a wedge error of the master elements and/or the coupling elements is reduced individually and to one another as much as possible. By moving the coupling elements in parallel with respect to the master elements, the flat optical contact could be impaired in the event of an undesirable wedge.

In a further preferred embodiment of the invention, the substrate bodies of the master elements are formed from a material which is an optical plastic. Preferably, the material of the substrate body is 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, fused silica, B270, N-BK7, N-SF2, P-SF68, P-SK57Q1, P-SK58A and/or P-BK7.

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

The selection 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 preferred that a substrate body is colored in order, for example, to filter light in a wavelength-selective manner in order to generate a hologram with a specific wavelength. In this way, a broadband light source can be used to expose different master holograms.

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

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. B. a rotation speed of an unwinding roller, winding roller, lamination roller, transport roller, 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. The control unit preferably comprises a processor, a memory and computer code (software/firmware) to control the components of the device.

The control unit may also include 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 includes a computer-usable or computer-readable medium, such as a hard drive, a random access memory (RAM), a read-only memory (ROM), a flash memory, etc., on which a computer software or code is installed. The computer code or software that controls the components of the device can be written in any programming language or model-based development environment, such as: B. without limitation in C/C++, C#, Objective-C, Java, Basic/VisualBasic, MATLAB, Python, Simulink, StateFlow, Lab View or Assembler.

The term "control unit is configured to" perform a particular 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 and initiates and regulates these operating steps.

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

It may be advantageous for the control unit to instruct an actuator to bring 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 assembly line, a turntable or a pick-and-place robot, to name just examples. In this way, the placement of master elements in the correct order can be partially or fully automated, reducing the risk of human error.

It may also be preferred that the control unit is configured to signal the next master element or the next n master elements to a user. This can happen in different ways, for example visually or acoustically. As an example of a visual signal, the controller may be configured to activate a light at the location of the next master item, e.g., the corresponding shelf, box, cart, etc.

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

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

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

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

- a light intensity with which the master element should be exposed,

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

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

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

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.

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

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 that is permanently or removable on the master element Identification can be attached. Additionally or alternatively, the ID feature may not be on the master element, but rather on its storage location. Preferably, the ID feature is applied to an area of the master element that does not cross the path of a light beam used for exposure. This area is preferably located on a different surface of the master element than the at least two optically accessible surfaces.

By controlling or monitoring the identities of the master elements placed and exposed in the first support 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 carried out. Another 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 need to be serviced or replaced. For example, depending on the number of uses, possibly weighted by the intensity of an exposure, corresponding master elements can be replaced before degradation of the master elements leads to loss of quality.

In a preferred embodiment of the invention, the method includes an arrangement of the master elements in two parallel rows. By using at least two rows, the size of the master elements can be reduced even further while making optimal use of the entire width of the composite membrane. If changes are required in a portion of a larger master hologram to be replicated, these can also be made on a smaller scale. In addition, the efficiency of the method can also be improved, since a higher number of identical or different master holograms can be replicated at the same time.

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 a first row can reach a master element in the second row behind it in the beam direction. This further increases the efficiency of the process, as two master holograms can be replicated at the same time using one light source.

Likewise, it may be preferred 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, the spacer preferably being part of the first carrier means. The light-absorbing spacer prevents unwanted Light from one master element penetrates into another, thus avoiding optical interference such as cross-talk. This is particularly advantageous if the master elements of the different rows are to be exposed from different angles or with different wavelengths.

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

Relief holograms are formed by physical contact between a deformable sensitive layer and a master hologram, such that the diffraction pattern of the master hologram is impressed into the sensitive layer.

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). A volume hologram is preferably written into the composite web. This can preferably be done using a transmission or reflection technique. Interference between object and reference beams within the hologram volume preferably creates a sequence of Brag levels. A volume hologram therefore preferably has a non-negligible extent in the direction of propagation of the light rays, with the Bragg condition applying to the reconstruction on a volume hologram. For this reason, volume holograms have wavelength and/or angle selectivity. The ability of volume holograms to store multiple images at the same time 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 the holograms. The three beams of rays preferably simultaneously illuminate a part of the composite web at the same angles. After exposure, three holograms are stored in the volume hologram at the same time. To reproduce the color hologram, it can be used that each partial hologram can be reconstructed solely using the color with which it was recorded. The three reconstructed color separations therefore overlap to form a colored, true-to-original image, provided the color components are correctly weighted.

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

The light source for a reflection hologram can be arranged so that the reference beam is incident on the composite web at a desired direction, preferably at a direction which is desired in the 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 in such a way that the reference beam falls downwards onto the composite web in a predetermined direction. The reference beam is preferably at least partially reflected back into the composite web by the master element in the form of an object beam. The reference beam and the object beam enter the photopolymer composite from opposite sides and interfere in its light-sensitive layer to replicate the hologram.

Transmission holograms are transmissive holograms in which the light from a light source is transmitted and diffracted by it. Preferably, an incident direction of the reference beam (preferably an incident light beam from the light source) and the object (in this case the master hologram) can be arranged on the same side of the composite web. 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 web, the reference beam and object beam with the same beam direction are superimposed to produce the replicated hologram.

In the case of a transmission hologram, it may be preferred to arrange the light source in such a way that the composite web can be exposed by a reference beam and object beam from the same side. The light source is preferably oriented with respect to the master element in such a way that a light beam first passes through the master element and the master hologram before reaching the composite web. The light source can preferably be arranged so that it passes from a side surface through a transparent master element. The light source can also preferably be arranged so that it falls onto the composite web through an upper and/or lower surface of the master element. The incident light beam is preferably refracted by the master element in such a way that a reference beam and an object beam are created, the object beam preferably corresponding to the portion of the light that is diffracted by the master hologram. The object beam preferably interferes with the undiffracted reference beam in the composite web to replicate the hologram.

In preferred embodiments of the invention, one or more master elements can be used to expose the composite web in order to form a transmission hologram therein replicate. Preferably, the replicated transmission hologram may be designed 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 backlit so that the holographic image can be reconstructed using light incident essentially from back to front. It may also be preferred that one or more master elements be 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 be used, for example, in a glass pane with light sources hidden at the edges. The replicated reflection hologram can also be configured to be front-lit. 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 sheet of glass, for example of the type disclosed in WO2020157312A1, to produce a holographic image when viewed orthogonally by reflecting light from hidden light sources along a predetermined path. It may also be advantageous for one or more master elements to be used to expose the composite web to produce a hologram that includes both a reflection hologram and a transmission hologram.

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.

Various techniques for exposing the composite web with the master elements using different reference beam angles and generating different types of holograms are explained in the detailed description based on the illustrations. We note that these techniques may, where appropriate, be combined with each other and with different structural arrangements of the device. An important advantage of the present invention is that preferably multiple types of exposure can be performed in the same device and in the same run.

The method preferably takes place using a device for replicating a plurality of holograms, comprising a first carrier means for an arrangement of a sequence of master elements from a plurality of master elements depending on a plurality to be replicated of holograms so that upper surfaces of the master elements are aligned in a horizontal plane, a lamination module for releasably laminating a photosensitive composite web to the aligned upper surfaces of the master elements, and an exposure module for exposing the master elements in order to

to replicate master holograms in the light-sensitive composite web, and a detachment module for detaching the exposed composite web from the master elements, the master elements being releasably introduced into the first carrier means, so 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 also introduced into 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.

The average person skilled in the art will recognize that technical features, definitions and advantages of preferred embodiments of the method according to the invention also apply to the device used for it, and vice versa.

For the purposes of the invention, a “module” preferably refers to a work station 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, but do not have to be. For the purposes of the invention, it may be preferred that the lamination module, the exposure module and the detachment module are located in the same housing.

The use of the device has the advantage that several master holograms can be exposed in a single series and at the same time there is great flexibility in the exposure method. By providing a variety of master elements and arranging them linearly, the size and weight of each master element can be reduced.

Using multiple smaller master elements to cover an area that would normally be covered by a single large master element can reduce the complexity of a system. Minor changes or defects to a master element do not require the replacement of all master elements. This reduces costs enormously. 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 These can be stacked to save space, transported without special lifting devices and can be easily inserted or removed from the device.

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 instead of simply placing the light-sensitive material on the master elements, a particularly homogeneous contact can be created between the master element and the light-sensitive material, which effectively avoids bubbles or wrinkles. By using a composite web made of the photosensitive material, this can be done repeatedly via the arrangement of the master elements in an efficient manner, so that the composite web flows while the arrangement of the master elements preferably remains stationary. In particular, a removable lamination makes it possible to remove the composite web without damage or residue and to continue running it through 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.

The detachment module preferably ensures a residue-free detachment of the composite web with sufficient force from the master elements without damaging the web.

The integration of the lamination module, exposure module and detachment module in the same device makes it possible to make the device very compact, which is particularly suitable for small series and customer-specific end products.

The lamination module preferably includes a lamination roller. This can be accommodated in the device in a height-adjustable manner and can roll along a predetermined path in order to press the composite sheet onto the top of the master elements. It may be advantageous for the lamination roller to be accommodated such that it can move along a predetermined path, the lamination module preferably comprising an actuator for moving the lamination roller along this path. Preferably, the path includes diagonally lowering the laminating roller from a first height and a first lateral position that is not directly above the first support means toward an upper surface of a first master element. The path preferably also includes horizontally rolling the lamination roller at a second height, lower than the first, along the top of the master elements until it reaches a final master element n of the sequence. The laminating roller is preferably configured to be maintained 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 laminating roller are designed to bring the laminating roller from a storage position to a laminating position on the top of the master elements. This height adjustment preferably includes 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. The person skilled in the art is aware of suitable means for such a height adjustment. The lamination roller can thus be brought outside an area between the master elements and/or coupling elements and/or light source before or after lamination. This creates greater degrees of freedom in the application of the coupling elements and/or the exposure of the master elements.

In a further preferred embodiment of the invention, the means for adjusting the height of the lamination module are also configured for adjusting the height of the lamination roller. Preferably, the means for adjusting the height of the laminating roller are set up to adjust the height of the laminating roller up to +/- 50 pm, preferably +/- 100 pm, particularly preferably +/- 500 pm. The height adjustment is preferably carried out 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 laminating roller can be translated for height adjustment.

Such a height adjustment can advantageously compensate for the smallest variations in the position of the surface or in the surface quality of the master elements. The master elements and the first carrier means 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 tilting position of the first support means can be compensated for in this way, unless the first support means is designed to be tiltable anyway, as explained above. These measures improve the optical contact between the composite web and the master elements while avoiding excessive lamination pressure.

In a further preferred embodiment of the invention, the lamination roller is initially brought to a predetermined position on the surface of the master elements and then its height is adjusted by smaller movement steps. This allows the lamination roller to be brought particularly precisely onto the actual surface of the master elements. The height adjustment of the laminating roller is preferably pressure-controlled. One or more sensors, in particular a pressure force sensor, can be used for this. Preferably, it is determined by means of a pressure force sensor that a laminating roller is in contact with the surface of the master elements with a pressure in a predetermined range. The pressure sensor can be present, for example, as a film on the surface of the lamination roller.

In a further preferred embodiment of the invention, the lamination roller is spring-mounted, the spring-loaded bearing preferably being configured for a height tolerance of at least +/- 50 pm, preferably +/- 100 pm, particularly preferably +/- 500 pm. Such suspension can compensate for tolerances in the surface quality and/or relative positioning of the master elements and the laminating roller. The suspension can further eliminate air gaps and/or bubbles between the master elements and the laminating roller and thus improve the optical contact between the composite web and the master elements.

The spring-loaded mounting of the laminating roller is preferably carried out mechanically (electro-jmagnetically, hydraulically or pneumatically, with a 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.

In a further preferred embodiment of the invention, the first carrier means and/or the second carrier means comprises one or more sensors for detecting contact with a further process component. It is preferably determined by means of a pressure force sensor that the first carrier means is in contact with a laminating roller and/or with the second carrier means with sufficient pressure.

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

In a preferred embodiment, a coherent light beam is emitted by the light source. Coherence preferably describes 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 present, for example, for parallel light rays. A temporal coherence preferably represents a fixed phase relationship between wave trains along the Direction of propagation and is particularly given for narrow-band, preferably monochromatic light beams.

The coherence length preferably refers to a maximum path length or transit time difference that two light beams have from a starting point, so that a stable (spatially and temporally) interference pattern is created when they are superimposed. The coherence time preferably refers to the time that the light needs to travel a coherence length.

In preferred embodiments, the light source comprises a laser. Particularly preferably it is a narrow-band, 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.

Other light sources, preferably coherent light sources, can also be used. Narrow-band light sources are preferred, preferably monochromatic light sources, which include, for example, light-emitting diodes (LEDs), optionally in combination with monochromators.

For replication with different wavelengths, it may be preferred to use illumination radiation in different wavelength ranges, for example 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).

For example, a laser system with three monochromatic lasers or one polychromatic laser with laser emission in the red, green or blue (RGB) range can 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 such that the wavelength at which the composite web is exposed can be adjusted.

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

In a preferred embodiment of the invention, the detachment module comprises a detachment roller which is positioned below a height position of a composite web. Preferably, the release module includes an actuator for moving the release roller along a path after exposure. Preferably, this path includes lifting the detachment module so that a composite web+ lying above it is also lifted.

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.

In a further preferred embodiment of the invention, the device comprises a transport module for transporting a light-sensitive composite web over the sequence of master elements. The transport module preferably comprises one or more transport rollers, for example a pull roller, which moves the composite web forward. This can result in a semi-continuous process with a roll-shaped intermediate product that can be passed on to further work stations for cutting.

In a preferred embodiment of the invention, the device also includes a fixation module. This ensures an even more compact device and increases the quality of the end product, as fixation can take place immediately before optical or mechanical disturbances affect the composite web that has just been exposed.

In a further preferred embodiment of the invention, the device comprises a control unit. The control unit preferably comprises a processor and a memory is preferably set up to control a selection and optional arrangement of the sequence of the master elements, the processor reading sequence data from the memory and signaling an actuator and/or a user in which sequence the master elements should be arranged are.

The control unit can thus preferably ensure that the master holograms are arranged in the first carrier means in a predetermined order, such as an order in which larger components, which integrate the replicated holograms, are processed on a parallel production line.

Preferably, the method according to the invention is 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 include a substrate body and at least one master hologram, selected from the plurality of Master elements, a sequence of master elements can be selected depending on the plurality of holograms to be replicated.

Detailed description

The invention will be explained in more detail below using examples and illustrations, without being limited to these.

Short description of the illustrations

Fig. 1 is a schematic representation of a device for carrying out the method according to the invention.

Fig. 2 is a schematic representation of a further preferred embodiment of the device in which coupling elements are used.

Figure 3 is a schematic representation of a preferred embodiment of the device in which light absorbing spacers separate the master elements and coupling elements.

Fig. 4 is a schematic top view illustrating an exchange of master elements in a first carrier means.

Figure 5 is a schematic top view of an arrangement of master elements in two rows in a first support means.

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 delamination, F) after Detachment.

Fig. 7 is a schematic front view of a reconstruction of an edge-lit

reflection hologram.

Figure 8 is a schematic front view of a reconstruction of an edge-lit

Transmission hologram.

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

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

Figure 11 is a schematic front view of an exposure process for replicating a top-exposed reflection hologram. Figure 12 is a schematic front view of an exposure process in which a multiplex hologram comprising both a reflection hologram and an edge-lit transmission hologram is replicated.

Figure 13 is a schematic front view of an exposure process in which a transmission hologram is exposed from below.

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.

Figure 15 is a schematic front view of an exposure process in which edge-lit transmission holograms are simultaneously exposed from both sides of a first two-row support.

16A - 16F show an example of the use of a wedge-shaped coupling element with an optical liquid.

17A - 17F show an example of the use of a cylindrical coupling element with an optical liquid,

Detailed description of the images

Figure 1 shows a schematic representation of a device 1 for carrying out the method according to the invention. For simplicity, the exposure and detachment modulus are not shown. The figure shows schematically a first support means 10, which holds a linear arrangement of five master elements 2 in such a way that the horizontal top 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 to one another or to a stationary surface. However, any embodiment of the first support means 10 can be used, for example 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.

Preferably, the first support means 10 can, for example, comprise a frame element along a lower outer edge of the master elements 2, which 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. For the purposes of the invention, such side surfaces are preferably viewed as optically accessible surfaces. 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 membrane 3. However, the composite sheet 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 done by directing light onto one or more of these optically accessible surfaces. An unlabeled underside of the master elements 2 can also be visually accessible, in particular if a first support means 10 with a corresponding frame structure is selected. The range of angles from which the exposure can take place is therefore very large and suitable for a wide variety of exposure arrangements

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

Fig. 2 shows a schematic representation of a further embodiment of the device

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.

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

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 an individual 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.

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 numbers). The coupling elements 8 comprise a transparent block made of a preferably identical material as 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 its top side is not visible, the top side is flush with that of the first support means 10 and the master elements 2. Also shown in Fig. 3 is a series of light-absorbing spacers 4, which separate the coupling elements 8 from one another, so 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 preferably means that the spacers 4 are arranged along the surface that separates a master element 2 from an adjacent master element 2.

Fig. 4 is a schematic top 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 based on the case principle according to the invention. For example, the master element C can be removed by moving it horizontally, for example. 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 an example of 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.

Fig. 5 is a schematic top view of a two-row first carrier means 10, which comprises eight master elements A - H. By being able to provide a larger number of master elements 2 of the same size as in Fig. 4, the process can be accelerated since more holograms can be produced per pass. The size of the first support means 10 is adapted to accommodate a larger number of master elements 2 in two rows.

Fig. 6 is a schematic side view of a further embodiment of a device for carrying out different process steps during replication of the holograms

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 individual row and their length determine the repeat length or “repeat length” 20. The arrows on the laminating roller 7 in Figure 6A indicate that the laminating roller 7 moves vertically (up/down). In order to enable the composite web 3 to flow between passes, the laminating roller 7 is advantageously in a first position above the first carrier 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 positioned laterally during the flow of the composite web 3 so that it is outside the space between the coupling elements 8 and the master elements 2. This enables free vertical movement of the coupling elements 8 in the space between them and the master elements.

At the beginning of the laminating 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.

As also shown in Fig. 6A, the coupling elements 8 in this embodiment include 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.

Figure 6B shows the positions of the various elements of the device 1 during the lamination process. The lamination roller 7, which encloses the composite web 3 between itself and the first support means 10 and/or the master elements 2, rolls horizontally in an upstream direction (to the left in the figure). This can result in an upstream roll of the composite web 3 being passively unrolled. The lamination brings the composite web 3 into optical contact with the top sides of the master elements 2. During the horizontal movement of the laminating roller 7, the coupling elements 8, which are housed on a second support 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 with one another in order to ensure rapid application of the coupling elements 8 without the risk of mutual interference.

Figure 6C shows the positions of various elements of the device during exposure. The coupling elements 8 are lowered to such an extent that the coupling sections 9 come into contact with the composite web 3 and are pressed elastically against the top of the master elements 2. In this way, the coupling sections 9 ensure a particularly homogeneous and complete 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 designed in various ways, including one or more light sources , mirrors, lenses, color filters, axes, and motors. Figure 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.

6E shows the device 1 during a detachment step in which the composite web 3 is detached from the top of the master elements 2. To do this, the laminating roller 7 is moved horizontally to the right. Preferably, a release roller located in front of the master elements 2 (not shown) can be raised upwards. The composite web 3 is arranged above the detachment roller, so that it is also raised by lifting the detachment roller.

Fig. 6F shows device 1 after the detachment step. The coupling elements 8 were completely raised to their first height and the composite web 3 was 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. In addition, 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 fixation module. The flow of the composite web 3 is preferably effected by a transport roller (not shown).

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

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 the 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 shows schematically the total internal reflection caused by the interface. The angle at which These totally reflected rays hit the reflection hologram 13 is crucial for its reconstruction. The totally reflected rays are reflected by the reflection hologram 13, which is shown by the dashed arrows. The holographic image produced is thus essentially orthogonal to the surface of the hologram 13, which facilitates readability when placed, for example, in a vertical surface. The illumination is referred to as edge-lit because the reconstruction beam hits the hologram or the substrate body 14 essentially from the side.

Such a hologram can advantageously be used in glass panels that are illuminated from a side edge so that the light source remains compact and hidden. Essentially, holographic imaging is 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.

The edge-lit reflection hologram 13 can function as a master hologram. In order for the replicated holograms to produce holographic images that are visible from the desired angle, the master hologram and the light-sensitive composite web must be exposed from an appropriate angle during reproduction. This can be done with the help of embodiments of the device and the method according to the invention, as explained further below.

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 the reconstruction, a reconstruction beam 19 is directed obliquely upward onto a side surface of the master element 2, so that the beam hits the transmission hologram 16 at a suitable angle. The beam 19 is refracted through the transparent substrate body 14 of the master element 2 and hits the transmission hologram 16 at this angle. When passing through the transmission hologram 16, the reconstruction beam 19 is at least partially diffracted by the edge-lit transmission hologram 16 to produce a holographic image.

In this example too, the beams 12 for forming the holographic image are essentially orthogonal to the surface of the hologram. This can make viewing easier, depending on the position of the hologram 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 web 3. To ensure the desired reconstruction angle, the Master hologram 6 and the composite web 3 are exposed at exactly the same angle at which the reconstruction beam 19 hits the edge-lit transmission hologram 16 in Fig. 8.

Particularly in edge-lit holograms such as those shown in the examples of FIGS. 7 and 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.

9 is a schematic front view of an exposure process for replicating an edge-lit reflection hologram 13 with the aid of 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 web 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 web 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 hit the light-sensitive material from different sides, so the replicated hologram is a reflection hologram. The reference number 17 shows schematically the two interfering beams.

A reconstruction beam 19 can be used to show the reflection hologram. The reconstruction beam 19 is reflected by the microstructure of the exposed light-sensitive material in the direction of the dashed line with the reference number 12, as explained in more detail for FIG. 7.

10 is a schematic front view of an exposure process for replicating an edge-lit transmission hologram 16 using a coupling element 8. A reference beam 11 falls 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 in order 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 disrupt the exposure, are avoided. This optical contact is also achieved by laminating the composite sheet 3 onto the master element 2, the optional use of optical liquids and the appropriate selection of materials with similar refractive indices.

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

Figure 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 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 passes through the composite web upwards 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 under different beam directions, the replicated hologram is a reflection hologram.

Figure 12 is a schematic front view of an exposure process in which a multiplex hologram is replicated. The master hologram 6 includes 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 Figure 10. In order to generate the reflection hologram, a further 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 upwards, on the other hand, show the diffracted object beams of the transmission hologram, which interfere with the undiffracted portion of the reference beam 11 incident obliquely from below to produce an edge-lit transmission hologram 16 in the composite web 3.

With this arrangement, it can 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, which is 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.

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

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 so 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 so that the optical signal generated by the reconstruction of both holograms is in the same direction as through the two types of shown by dashed arrows.

15 is a schematic front view of an exposure process in which two edge-lit transmission holograms 16 are simultaneously exposed from both sides of a first carrier means 10 with two rows. In this example, the first carrier means 10 is configured such that that it includes two rows of master elements 2. The two rows are separated by a light-absorbing spacer 4. In addition, the coupling elements 8 in the second carrier means are separated by an analog light-absorbing spacer 4. The spacers 4 keep a buffer in the composite web 3 free from exposure. In addition, the composite web 3 can be exposed from two directions simultaneously, as shown in the figure. This increases the speed of the procedure. In this exemplary embodiment, the exposure method replicates a transmission hologram 16 on both master elements 2 shown in a composite web 3. However, it is entirely possible for each master hologram 6 to be exposed from a different angle and/or to produce a different type of hologram. Thanks to the light-absorbing spacer 4, the reference beam 11, which is used to expose a master hologram 2, does not penetrate into the neighboring hologram. This prevents disruptions such as “cross-talk” and increases the quality of the holograms produced.

Figures 16A - 16F show schematically an embodiment of the invention, wherein the coupling element 8 is pushed over the surface of the composite web 3 with an optical liquid 29. In this embodiment, the coupling element 8 has a prismatic shape with a trapezoidal cross section, the shortest side of the trapezoid corresponding to a contact surface 30 which is 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.

Figure 16A shows a first phase of the method. The master elements 2 are provided in a first carrier means 10 so that their surfaces are essentially flush. A composite track 3 is provided for replication of the master elements. The composite web 3 is laminated onto the flush surfaces of the master elements 2 using a lamination roller 7. For this purpose, the lamination roller 7 is brought from a storage position onto the surface of the master elements 2, so that the composite web 3 is located between the lamination roller 7 and the master elements 2.

When positioning the lamination roller 7 on the master elements 2 before lamination, the lamination roller 7 can be moved, in particular rolled, along a plane comprising the surface of the master elements 2. Optionally, the lamination roller 7 is also lowered down to the level of the surfaces of the master elements 2. For this purpose, means for adjusting the height of the lamination 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 preferred to also adjust the height of the lamination roller 7. For this purpose, the lamination roller 7 can be lowered in steps of, for example, 50 pm until a desired pressure between the lamination roller 7 and the master elements 2 is achieved. Achieving the The desired pressure can be detected by a suitable sensor. After reaching the pressure or after positioning and adjusting the lamination roller 7, it is rolled over the surface of the master elements 2 in order to bring the composite web 3 into mechanical and optical contact with the master elements 2 without gaps and bubbles. Rolling of the lamination roller 7 is indicated by a horizontal arrow pointing to the left.

16B shows a further phase of the process after the lamination of the composite web 3 onto the surface of the master elements 2. A metering unit 28 for metering optical liquid 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 metering unit 28 applies a quantity of optical liquid 29 to the master element 2, the quantity of the optical liquid 29 being designed to cover a contact surface between the coupling element and the composite web. The dosing unit 28 is then brought back into its storage position, as shown in FIG. 16C.

16D shows schematically, with the arrow pointing downwards, the height adjustment of the coupling element 8 in order to bring the coupling element 8 from a storage position to a proximity to the master elements 2. 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 web 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 web 3, so that the optical liquid 29 is located between the coupling element 8 and the composite web 3. The optical liquid 29 crosslinks both with the contact surface 30 and the composite web 3 due to capillary forces. The optical liquid 29 thus completely excludes the gap between the contact surface 30 and the composite web 3. Since the optical liquid 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. In addition, the optical Liquid 29 acts 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 liquid 29 to inevitably follow the contact surface 30 as it moves along the surfaces of the master elements 2. This is shown schematically in Figure 16F.

During the movement of the coupling element 8 over the surface of the master elements 2, exposure takes place synchronously. For this purpose, a scanning reference beam 11 is directed onto the coupling element 8 in such a way 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, for example by moving a laser itself 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). In order to overcome the capillary forces and avoid deformation or distortion of the composite web, the coupling element 8 is preferably moved laterally/elongated and upwards in a continuous movement. Any suction effect is advantageously avoided or reduced.

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 liquid 29 is introduced to improve the optical contact between the coupling element 8 and the composite web 3.

17A shows a lamination step in which 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. 17B and 17C show the application of a quantity of optical liquid 29 to the composite web 3. This is done - analogously to the embodiment of FIGS. 16A - 16E - by means of a height-adjustable metering unit 28. During these steps, the cylindrical coupling element 8 remains in a storage position, which in this embodiment is located above the level of the laminated composite web 3.

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 carrier means 10 or a master element 2. In this case, this positioning of the coupling element 8 includes a downward movement, which is made possible by the height-adjustable mounting of the coupling element 8. The downward movement is schematically represented by the downward arrow in Figure 17D.

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 liquid 29 is located between the coupling element 8 and the composite web 3. The optical liquid 29 crosslinks both the contact surface 30 and the composite web 3 due to capillary forces. The optical liquid 29 thus completely excludes the gap between the contact surface 30 and the composite web 3. Since the optical liquid 29 has one 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.

Since the cylindrical coupling element 8 contacts the composite web 3 only along a thin line or axis, the contact surface 30 between the cylindrical coupling element 8 and the composite web 3 is smaller than the contact surface 30 between the wedge-shaped coupling element 8 and the composite web 3. A smaller amount of optical liquid 29 is therefore sufficient to bridge the interface between the cylindrical coupling element 8 and the composite web 3. Due to the capillary forces, the optical liquid 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 shown schematically in FIG. 17F.

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

Reference symbol list

F1 First face of a master element

F2 Second face of a master element

F3 Top surface of a master element

F4 Second side surface of a coupling element

F5 First side surface of a coupling element

1 device

2 master element

3 compound railway

4 spacers

5 absorber layer

6 master hologram

7 lamination roller

8 coupling element

9 coupling section

10 First carrier

11 reference beam

12 Reconstructed signal/object wave

13 Reflective Edgelite HOE

14 substrate bodies

15 Totally reflected beam

16 T ransmissions Edgelite HOE

17 Interference between reference and object beam

18 T ransmissions HOE

19 reconstruction beam

20 repeat length

21 cover

22 object beam

28 optical fluid dosing unit

29 Optical fluid

30 contact surface of the coupling element

Claims

PATENT CLAIMS 1 . A method for replicating 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), so that upper surfaces (F3) of the master elements are horizontal Level aligned, c. Removable lamination of a light-sensitive composite web (3) onto the aligned surfaces of the master elements (2), i.e. Exposure of the master elements (2) in order to replicate the master holograms (6) into the light-sensitive composite web (3), and e. Detaching the exposed composite web (3) from the master elements (2), characterized in that the master elements (2) are detachably introduced 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 the master elements (2) are introduced into the first carrier means (10) in such a way that two or more surfaces of the master elements (2) are optically accessible for the purpose of exposure. 2. The method according to claim 1, characterized in that the master elements are present separately in the first support means (10) along a linear arrangement, the master elements (2) preferably being separated by light-absorbing spacers (4) and/or being on vertical surfaces of the mast elements (2) a light-absorbing layer (5) is applied. 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 portion of the composite web (3) during exposure between the one or more coupling elements (8) and the master elements (2). 4. Method according to the previous claim, characterized in that the coupling elements (8) are arranged on a height-adjustable second support means, a lower surface of the coupling elements (8) preferably being 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 coupling element (8), preferably at least one lower surface of the respective coupling element (8) being congruent to an upper surface (F3). 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) have the same dimensions and preferably have a cuboid shape, the substrate bodies (14) preferably having a height between 1 - 10 cm and 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, the degree of polishing preferably being at least P3, the optically accessible surfaces preferably having an anti-reflective coating. 8. The 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 the master elements (2) is controlled by a control unit, the control unit comprising a processor and a memory, the processor reading sequence data from the memory and an actuator and / or a user by means of an interface signals the sequence in which the master elements (2) are to be arranged. 10. The method according to the previous 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 set the position, the path and / or the 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, the sensor reading an ID feature of the individual master elements (2) or a storage location of the master elements and sending the ID to the control unit for control and/or 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, the rows of the master elements (2) preferably being separated by a light-absorbing spacer (4), the spacer ( 4) is preferably part of the first carrier means (10).