Document body having a metastructure formed in a laminate in order to generate structural colours and method and device for the production thereof

Abstract

A document body has in its interior: an optically detectable physical representation (3) of information; and a metastructure (5) which gives the information a multi-coloured colouring. The document body is transparent. The invention further relates to a security document having a document body of this type and to a method for producing the metastructure and the document body and the security document. A metastructure is a microscopic structure that interacts with light, in particular by diffraction, thin-film interference, refraction, diffusion, resonance and / or reflection. A metastructure is usually a micro- or nano-structure, with structure sizes below the wavelength of radiation, and in particular having a plasmonic structure. The representation (3) can be an imprint, engraving or embossing.

Description

[0001] DOCUMENT BODY WITH A METASTRUCTURE FORMED IN A LAMINATE FOR THE PRODUCTION OF STRUCTURAL COLORS AND METHOD AND DEVICE FOR ITS MANUFACTURING

[0002] The present invention relates to a document body, particularly for an individualized document, comprising a multilayer laminate with data inscribed therein, wherein a marking is formed inside the laminate which represents the inscribed data at least partially by means of structural colors. The invention further relates to a method and a device for producing such a document body.

[0003] A wide variety of individualized, and especially personalized, documents, such as those in card or book form, are known from the state of the art. For example, book-like passport documents or individual pages thereof (e.g., the so-called "passport holder's page" or paper pages), identity cards, and many types of personalized chip cards, such as bank cards, credit cards, ID cards, membership cards, access cards, etc., or personal (mostly card-shaped) labels, all belong to the group of often individualized documents. In particular, such individualized, especially personalized, documents that are also security-relevant ("security documents"), such as passports or identity cards (e.g., national identity cards or access identification cards), must generally meet several criteria. For example, they must regularly demonstrate high resistance to potential environmental influences and a long service life.In the case of passport documents, typically up to 10 years.

[0004] Furthermore, the presence of one or often several security mechanisms to protect against forgery is frequently required. Such security mechanisms can be achieved, in particular, through the use of special materials and their targeted arrangement within the document and / or special manufacturing or processing methods (e.g., offset printing). Last but not least, the document must usually also be aesthetically pleasing, as government-issued identity documents are often seen as a calling card for the respective country and are intended to reflect not only the individual's identity but also that of the country itself.

[0005] A document of the aforementioned type (e.g., an identity card), or a document body thereof (such as a so-called data page of a passport, which may also include, for example, further pages and a cover), is in many cases composed of several layers, especially films (usually made of polycarbonate), between which, primarily in the case of a security document, individual security features (such as holograms or offset printing) may be located as protective mechanisms. During the production of the document, the individual layers are placed on top of each other and bond together under pressure and temperature during a lamination process to form a so-called document body, which is sometimes also referred to as a "monoblock" in technical terms.

[0006] A security feature on the outside of a document is more easily accessible and therefore generally easier to tamper with than one located inside the document, which is more difficult to access. Internal security features are better protected against direct influences – such as liquid chemicals or extraction from the document – ​​and thus contribute to greater document security.

[0007] This basic principle is also usually applied to the personalization or individualization of security documents, in particular to provide a security document with personal data, such as a passport photo or biometric information about the document holder to whom the security document is or will be issued.

[0008] The transmission of security-relevant data, especially personal data, is highly sensitive from both a security and data protection perspective. Therefore, the production of security documents is generally a multi-phase process. The first phase involves the production of the blank, consecutively numbered document body by a document supplier, followed by a subsequent phase in which the document is personalized in a protected environment, usually under the supervision of government authorities in the case of government security documents.

[0009] According to established techniques, color pigments and optical effects are often used to display information or data on security documents. However, these methods have limitations regarding durability and manufacturing complexity. Color pigments can fade over time or be affected by environmental factors. Furthermore, the production costs for highly specialized inks and pigments are often high, making the economical production of large quantities of security documents difficult. Another approach to displaying information, for example, in image, numerical, or text form, relies on personalization using a grayscale laser, such as one with a wavelength of 1064 nm (the so-called standard wavelength) or 355 nm (UV laser), or another wavelength suitable for the material being processed and the desired resolution.For this purpose, one or more areas, particularly layers, of the security document are laser-reactive and turn black under the influence of the laser radiation. Personal data such as name, date of birth, or image thus become part of the monoblock and are therefore better protected against forgery attempts and environmental influences. However, such a data representation, e.g., image or text, is binary (e.g., black and white or black and transparent) or only exhibits several shades of gray. It is not a color representation of the data, i.e., not a representation with multiple colors, including at least one color other than black, white, and shades of gray.

[0010] A well-known technique for creating color images in security documents involves printing a color image onto a film and inserting this film—as an insert—into the multi-layered security document or the document body before the lamination process. This means that customer-specific personalization is only possible before the document is produced. The process is therefore complex and feasible in only a few projects.

[0011] In addition to the use of color pigments, the use of structures to create structure-based colors, so-called structural colors, is also known for the production of color images.

[0012] WO 2016 / 198657 A1 describes a method for geometrically modifying plasmonic structures on a support structure. In this process, a specific geometry of a subset of the plasmonic structures is altered by photothermal, or at least partial, melting. This modifies the optical properties of the overall structure. In particular, this method can be used to create structures for generating structural colors.

[0013] WO 2018 / 122208 A1 describes a method for geometrically modifying high-refractive-index dielectric structures on a support structure. The method includes providing a support structure, and a first plurality of high-refractive-index dielectric structures are supported by this structure. The specific geometry of a subset of the dielectric structures is modified by photothermal melting of at least a portion of each of the affected dielectric structures using incident electromagnetic radiation. This method can also be used, in particular, to create structures for generating structural colors.

[0014] It is an object of the invention to provide an improved document body (monoblock) as well as a method and a device for its manufacture in such a way that a multicolored marking is formed or is formed inside the document body, which represents data inscribed therein.

[0015] To solve this problem, the respective devices or methods are proposed according to the teachings of the independent claims. Various embodiments and further developments of the solution are the subject of the dependent claims.

[0016] Some terms used here to define the present solution are explained in more detail below:

[0017] The term "document body," as used herein, refers to a physical body in the form of a sheet or card that already constitutes a document or at least an information-bearing page thereof, or is configured for this purpose or pre-configured (e.g., as a blank document to be individualized, especially personalized). In particular, card-shaped security documents such as bank or credit cards, identity cards, or data pages of book-like identity documents, especially passports, are each document bodies in the aforementioned sense.

[0018] The term "color" and its variations (e.g., "colored"), as used herein, refers to any color other than black, white, and shades of gray obtained solely from mixing black and white. In particular, color can be a color from a predefined color space, such as one of the well-known RGB (red / green / blue) or CMY (cyan / magenta / yellow) color spaces. The term "color" is to be understood here as independent of the method of its production. Specifically, color need not necessarily be produced by color pigments, but can also be generated in other ways, such as through resonances, interferences, etc., as is the case with structural colors. With regard to the subsequent definition of "light," "color" can also refer to wavelengths outside the visible (VIS) range of the electromagnetic spectrum.The term "multicolored", as used herein, with regard to a multicolored object, in particular a mark in the document body, is to be understood as containing at least two colors or at least one color (each as defined above) and additionally, white, black or at least one shade of gray.

[0019] The term "security document" has already been explained previously.

[0020] The term "optically perceptible physical representation of information," as used herein, refers to a physical, i.e., not merely virtual, representation of information on or in a physical body. In particular, the physical representation can be formed on or in the body by means of characters, writing, or images, for example, through printing or local material transformation with associated material discoloration, e.g., through laser processing. Specifically, characters, writing, or images formed on or in a document are each physical representations of information. Consider, for example, the personalization data displayed on or in an identity card, such as name, date and place of birth, biometric characteristics, etc., and / or a photograph of the cardholder, or official symbols or visible ("overt") security features.“Optically detectable” here means that the information represented by the physical representation can be detected optically, i.e., by evaluating light emitted by the physical representation, whether by reflection, diffraction, scattering and / or emission, with the human eye (for light in the visible spectral range) and / or image sensors.

[0021] The term "metastructure," as used herein, refers to an artificially produced (i.e., engineered) microscopic structure of a body, in particular one of its surfaces ("metasurface"), which interacts with electromagnetic radiation, especially visible light, due to its structure (in particular by diffraction, interference, especially thin-film interference, refraction, scattering, resonance, and / or reflection), thereby enabling the manipulation of various optical properties and functionalities. A metastructure is generally a micro- or nanostructure with structure sizes below the wavelength of the radiation, in particular below half its wavelength. It may, in particular, exhibit a plasmonic structure, especially a surface structure.In this case, a metastructure has the particular property that, when irradiated with electromagnetic radiation from a wavelength range suitable with regard to its structural sizes, it can generate structural colors. The term "support substrate," as used herein, refers to a solid, usually monolithic, substrate on which the metastructure is or is formed.

[0022] The term "structural colors" (or "structural coloration"), as used herein, refers to colors that arise from specific structures through optical effects caused by those structures, without the involvement of pigments. The aforementioned metastructures are particularly relevant as such structures. Structural colors can be combined with pigment-based colors, so that the resulting color representation is determined partly by the structural colors and partly by the pigment-based coloration. A well-known example of structural colors are those that occur structurally on bird feathers or butterfly wings and are not pigment-based.

[0023] The term "light," as used herein (in a somewhat more general sense than usual), refers to electromagnetic radiation whose wavelength(s) lie wholly or partially within at least one of the following spectral ranges of the electromagnetic spectrum: infrared radiation (IR), visible light (VIS), ultraviolet light (UV). The portion of the spectrum spanned by these spectral ranges thus lies in the wavelength range from 200 nm to 50 pm, preferably in the wavelength range from 315 nm to 3 pm (near UV to near IR), or solely in the visible range VIS (380 nm to 780 nm).

[0024] The well-known acronym "CAD" (English "computer-aided design") refers to the support of design tasks using electronic data processing for the production of a product, in particular the creation or modification of a virtual model of the product.

[0025] Any terms used herein, such as "includes," "contains," "includes," "has," "with," or any other variant thereof, are intended to cover non-exclusive inclusion. For example, a method or apparatus that includes or has a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent in such method or apparatus. Furthermore, unless expressly stated otherwise, "or" refers to an inclusive OR (OR) and not an exclusive OR (XOR). For example, a condition A or B is satisfied by any of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0026] The terms "ein" or "eine," as used here, are defined as "one or more." The terms "ein anderer" and "ein Weitere," as well as any other variant thereof, are to be understood as "at least one more."

[0027] The term "plural", as it may be used here, is to be understood in the sense of "two or more".

[0028] The terms “first”, “second”, “third”, and similar terms in the description and in the claims are used to distinguish between similar or otherwise identically named elements and not necessarily to describe a sequential, spatial, or chronological order. It is understood that the terms used in this way are interchangeable under suitable circumstances and that the embodiments of the solution described herein may also function in orders other than those described or illustrated here.

[0029] The terms "configured" or "set up" to perform a specific function (and their respective variations), as used here, mean that a device or component thereof is already in a configuration or setting capable of performing the function, or at least adjustable—i.e., configurable—so that it can perform the function after appropriate adjustment. Configuration can be achieved, for example, by adjusting process parameters or by using switches or similar devices to activate or deactivate functionalities or settings. In particular, the device may have several predefined configurations or operating modes, allowing configuration by selecting one of these.

[0030] A first aspect of the present solution concerns a document body, in particular for a security document. It contains: (i) an optically perceivable physical representation of information, in particular an optically perceivable representation of an image and / or data in character and / or text form; and

[0031] (ii) a metastructure configured such that, when irradiated with light from a defined spectral range, it gives multicolored coloring to the information represented by the physical representation by means of structural colors generated as a result of the irradiation;

[0032] The document body is transparent or partially transparent to light from the spectral range, at least for a section of this spectral range, to such an extent that the metastructure can be illuminated by light from an external environment of the document body in such a way that the representation of the information colored by means of the structural colors generated thereby becomes optically perceptible (i.e. detectable) from the external environment of the document body, in particular visible to the human eye or a camera.

[0033] The coloring of the physical representation of information, such as a passport photo in a document body configured as a data page of an identity card, is therefore not carried out, at least partially, in the usual way exclusively or primarily by means of color pigments, but instead or primarily additionally on the basis of structural colors generated by means of the metastructure, i.e. due to optical effects such as diffraction, interference and / or resonance etc., on the metastructure, such as a plasmonic surface structure.

[0034] Since metastructures are difficult to produce due to their tiny structures, and in addition the structures should also correspond exactly to the desired color scheme of the pictorial representation, forgery is very complex and difficult, so that a high level of security with regard to the forgery protection of the document body can be achieved.

[0035] The following describes various exemplary embodiments of the document body, which, unless expressly excluded or technically impossible, can be combined with each other and with the other aspects of the present solution described below. In some embodiments, the physical representation of the information is designed such that the information is optically detectable from the external environment of the document body even when the metastructure is irradiated with diffuse radiation from the spectral range. In particular, no coherent radiation is required here (unlike, for example, holograms) to detect and, especially, verify the information, which increases the range of applications for the document body, as no coherent light sources are needed.However, it is possible that with diffuse irradiation, the coloration caused by the structural colors does not occur or occurs only to a limited extent, and thus additional verification aspects based on the structural coloration are not available. For example, a preliminary inspection of a document containing the document body can already be carried out with diffuse irradiation, while a subsequent further inspection is carried out under coherent irradiation (especially direct irradiation), perhaps only if the preliminary inspection is successful.

[0036] In some embodiments, the metastructure comprises a support substrate in or on which high-refractive-index dielectric and / or plasmonic structures are arranged for at least partial generation of the structural colors. This allows for material separation, enabling the selection of a material (or material combination) optimized for its function as a support substrate on the one hand, and a material (or material combination) optimized for the metastructure's fabrication and its effect on generating structural colors on the other. With regard to the metastructure, a material can be selected that has a relative dielectric constant of £ at a reference wavelength of 532 nm. r > 5, especially £ r > 6, £ r > 7, £ r > 8, £ r > 9, or £ r > 10.

[0037] In particular, the quantity of dielectric and / or plasmonic structures in at least one section of the metastructure can exhibit an arrangement of a large number of positive and / or negative structural elements (especially more than ten, more than one hundred, or more than one thousand), whose respective longest spatial extent and whose pairwise greatest mutual distance from the nearest neighboring structures in the arrangement are both smaller than the smallest wavelength from the spectral range, such that local radiation resonances can form in the arrangement. These radiation resonances can then contribute to, or even cause, at least a partial generation of the structural colors. The respective size of the structural elements, i.e.,The longest extent of each structure along a direction can be, in particular, 200 nm or below. The longest spatial extent and / or the greatest mutual distance between the nearest adjacent structures can be, in particular, at most two micrometers (< 2 pm), and in particular at most one micrometer (< 1 pm). Thus, metastructures with characteristic structures in the nanometer range are particularly suitable, allowing the use of short-wavelength irradiations with wavelengths of a similar order of magnitude (especially wavelengths approximately twice the size of one of the aforementioned structure sizes).

[0038] In particular, the arrangement of the structural elements of the multitude within the section can be so regular that the positions of the structural elements in the section each correspond to a grid point of a dot matrix, especially with a square or hexagonal grid geometry. This regularity in the arrangement can facilitate the production of the metastructure and / or the targeted use of resonances and / or interferences to generate the structural colors.

[0039] Specifically, the arrangement of the structural elements can be designed such that the coloration of the output radiation caused by the structural colors is sufficiently color-stable over a radiation angle range of at least 90° ± 30°, and in particular at least 90° ± 45°, that the wavelengths of the colors involved in the coloration change by no more than 50%, and in particular by no more than 30%, where an angle of 90° corresponds to a view orthogonal to a surface supporting the micro- or nanostructure. A small structural spacing and a structure size in the nanoscale range (below the wavelength of the incident light) can generate a high diffraction component (diffraction effect), resulting in stable color values ​​over a large viewing angle.This allows a high degree of color stability to be achieved over a significant angular range, thus promoting a corresponding robustness and reliability of such testing, particularly with regard to the inspection of security documents, since it then does not depend on an exact viewing angle of the document body in order to carry out a color-based, especially visual, inspection.

[0040] In some embodiments, the metastructure is made of a material or a combination of several materials which, assuming the absence of the structural elements and the structural colors they produce, is monochromatic or colorless when irradiated with white light, solely due to the material properties. The multicolored representation of the information can thus be defined exclusively by means of the structural colors, and pigmentation can be omitted or reduced to a monochromatic pigmentation. In some embodiments, the metastructure contains, either (i) including or (ii) excluding the carrier substrate, one or more of the following materials, individually or cumulatively predominantly, i.e., in the largest proportion relative to other materials or even in absolute terms exceeding 50%: plastic, metal, semimetal, dielectric material.

[0041] In particular, the metastructure, based on the amount of substance, may contain one or more of the following materials, individually or cumulatively, as the predominant component: aluminum, germanium, gold, silver, silicon, titanium. Specifically, the metastructure may be configured as a combination of (i) a plastic as the carrier material (material of the support substrate), (ii) a vapor-deposited layer comprising one or more of the aforementioned materials. Optionally, (iii) one or more intermediary or bonding materials may be added to connect the carrier material and the vapor-deposited layer.

[0042] The aforementioned materials or material combinations are particularly well suited for the production of the metastructure, especially with regard to the formation of its microscopically small structures.

[0043] In some embodiments, the document body features a multilayered laminate in which the metastructure is embedded. This provides the metastructure with good protection against external influences, particularly chemical or mechanical ones, while the multilayered laminate structure of the document body allows for easy integration of the metastructure during manufacturing. The metastructure can be applied to a substrate layer, then covered with at least one further layer, and finally bonded together with this and any additional layers to form the laminate.

[0044] In particular, the metastructure can be embedded, at least partially, as an insert in at least one layer of the laminate. The layer can, in particular, have a corresponding cavity or recess for at least partial accommodation of the metastructure.

[0045] In some embodiments, the metastructure is at least partially embossed into a layer of the laminate. This allows for particularly efficient production of the metastructure, either within an integrated manufacturing process for the document body or in a preliminary process where the metastructure is embossed into a component (such as a layer of the subsequent laminate) before this layer is integrated into the document body.

[0046] In some embodiments, the physical representation and the metastructure are integrally formed in the same layer of the laminate. In particular, this layer can contain the physical representation of the information in the form of a pigment-based color, such as printing, e.g., with shades of gray or as a black-and-white graphic, and the metastructure as an embossing within the layer. In this way, one layer can be eliminated, and the laminate can be made particularly thin.

[0047] In some embodiments, the metastructure is configured to both provide the optically detectable physical representation and generate the structural colors as a result of irradiation. In particular, the metastructure can be configured to represent the physical representation using color pigments and to modify the coloration caused by the color pigments, at least point by point or section by point, based on the structural colors. Additionally or instead, the metastructure can be configured to represent the information to be displayed based on the physical representation in a first color or colors from a first color space region, while other aspects of a representation generated by the metastructure are displayed in a second color or colors from a second color space region that is different from the first, and in particular, disjoint from it.

[0048] In some embodiments, the physical representation is formed in a first layer of the laminate, and the metastructure is formed in a second layer of the laminate, distinct from the first. The second layer can, in particular, be arranged directly on top of the first layer in such a way that the metastructure overlaps the physical representation, e.g., a print or laser-induced selective color change of the first layer, at least partially, in order to achieve the coloring of the displayed information based on the structural colors. In this way, the metastructure can be formed independently of the first layer, for example, in a separate process. This also ensures from the outset that the physical representation cannot be affected by the formation of the metastructure, e.g., by laser processing or embossing of the second layer.A second aspect of the present solution concerns a security document, in particular an identity document, having a document body according to the first aspect.

[0049] A third aspect of the present solution concerns a method for producing a metastructure configured to be integrated into the interior of the document body as a metastructure according to the first aspect, and to generate structural colors when irradiated with polychrome electromagnetic radiation from at least one spectral range of the electromagnetic spectrum.

[0050] The procedure indicates:

[0051] (i) Creating a master form as a negative for generating a surface structure of the metastructure in a subsequent embossing process using the master form as at least a partial embossing tool; and

[0052] (ii) Using the embossing tool having the master shape to process a plate- or sheet-shaped substrate by means of the embossing process in order to form the metastructure in the substrate by embossing in such a way that the master shape defines the shape of the metastructure at least partially.

[0053] The use of such a master form for producing the surface structure of the metastructure within an embossing process using the master form as a negative offers the particular advantage of achieving exceptionally high resolution for the structural coloration. This is made possible primarily by the fact that the material of the master form can be selected independently of the substrate material, allowing for the formation of very fine structures within the master form, for example, using laser sintering and / or electron beam lithography. The material of the master form can advantageously be chosen to be harder than the substrate material, even under the pressure and temperature conditions encountered during the embossing process. This ensures that the surface structure of the master form remains essentially unchanged during embossing, while the substrate surface is shaped by embossing based on the thus stable surface structure of the master form.

[0054] In some embodiments, the master form is defined in such a way that, in conjunction with the embossing process, it defines a multitude of positive and / or negative structural elements of the metastructure to be produced. When irradiated with light from the defined spectral range, these elements interact to generate at least a portion of the structural colors. As already mentioned in the preceding description of the document body, local radiation resonances can thus develop in the arrangement of the structural elements, which can then contribute to, or even cause, at least a portion of the structural colors.

[0055] In some embodiments, the master form is created, at least partially, using an additive manufacturing process controlled by a virtual 3D model of the master form to be produced. The structure of the master form can thus be defined as a virtual 3D model (3D CAD model), particularly using a 3D CAD process, and subsequently formed into a physical structure corresponding to the model using the additive manufacturing process. This makes it possible to create the structure virtually beforehand and optimize it flexibly and without material or manufacturing costs, for example through simulation, before the shape optimized based on the virtual 3D model is then translated into a physical surface structure of the master form.

[0056] The creation of the master mold can be achieved, at least partially, by electron beam lithography onto a substrate or by laser sintering. These methods are particularly advantageous for this purpose due to their ability to create exceptionally fine structures.

[0057] In some embodiments, the method involves forming the metastructure using a metallic thin film. According to a first embodiment, the thin film can be, in particular, the substrate itself or a layer thereof, into which the metastructure is embossed during the embossing process. According to another embodiment, the thin film can be applied subsequently to the metastructure already formed in the substrate during the embossing process, i.e., as a coating of the pre-formed metastructure. In both embodiments, the metallic thin film can serve to optimize, and especially maximize, the optical properties of the metastructure, particularly its reflection behavior (especially its reflectance).

[0058] Alternatively or additionally, the process can also involve applying a metallic thin film to the substrate prior to processing using the embossing process. A potential advantage of this is that it allows for a particularly high degree of homogeneity, especially with regard to the thickness of the thin film.

[0059] In some embodiments, the method further includes at least partial sealing of a surface of the resulting metastructure, defined at least partially by its shape through the embossing process using the master mold, with a protective layer containing lacquer and / or plastic. Such a protective layer can be particularly advantageous for protecting the surface structure of the metastructure and, if applicable, its coating with the aforementioned metallic thin film against external mechanical and / or chemical influences, thereby making the master mold more robust and ensuring high quality of the resulting metastructure, especially with regard to its optical effect in producing the desired structural coloration.

[0060] A fourth aspect of the present solution concerns a method for producing a document body according to the first aspect, in which a metastructure obtainable using the method according to the third aspect is integrated into the interior of the document body (particularly during its production) in such a way that the metastructure can be illuminated from the external environment of the document body with light in such a way that the representation of the information, colored by the structural colors generated in this process, becomes optically perceptible from the external environment of the document body, in particular visible to the human eye or a camera. This enables efficient optical verification of the document body or a security document containing it with regard to its authenticity or original condition and thus for the detection of any forgeries or attempted forgery.

[0061] In some embodiments, the metastructure located inside the document body is post-processed and modified using a photothermal process that acts on the document body from its surroundings. This results in a change in the coloration of the information represented by the physical representation, which is produced by the structural colors under the same spectral irradiation. This allows, in particular, subsequent individualization of the document body. It can thus initially be produced as a document body blank, including the preliminary metastructure integrated within it, which is also referred to herein more precisely as the "metastructure blank," and, if necessary,They can also be distributed, for example to spatially separated passport offices within a country, in order to be subsequently individualized, especially personalized, on-site (i.e., at the passport offices) in order to obtain a final metastructure 5. Such individualization can, in particular, involve adapting the raw metastructure to the corresponding individual customization of the resulting color scheme.

[0062] The features and advantages explained in relation to the first aspect of the solution also apply accordingly to the other aspects of the solution.

[0063] Further advantages, features and application possibilities of the present solution will become apparent from the following detailed description in the context of the figures.

[0064] This shows:

[0065] Fig. 1A according to a first exemplary embodiment shows a layered structure of a document body in which the metastructure is designed as an insert in one of the layers;

[0066] Fig. 1 B shows a layered structure of a document body according to a second exemplary embodiment, in which the metastructure simultaneously provides the physical representation of the information;

[0067] Fig. 1C according to a third exemplary embodiment shows a layered structure of a document body in which the physical representation and the metastructure are formed as separate structures in the same layer of the document body;

[0068] Fig. 2 shows a perspective view of the document body from Fig. 1A, Fig. 1B or Fig. 1C according to exemplary embodiments;

[0069] Fig. 3 shows a side view of a book-like document, in particular a security document (e.g. a passport), according to an exemplary embodiment, which contains a document body, e.g. from Fig. 1A, Fig. 1B or Fig. 1C, as a book page;

[0070] Fig. 4 according to an exemplary embodiment shows a perspective view of a light-coloring surface of a metastructure; Fig. 5 according to an exemplary embodiment shows a perspective view of a surface of a metastructure blank resulting from an embossing of a carrier substrate with positive structural elements arranged regularly in a grid before their individualization for adaptation to information to be displayed, e.g. to a passport photo of a person to be colored by means of the metastructure;

[0071] Fig. 6 according to an exemplary embodiment shows a perspective view of a surface of a metastructure blank resulting from the embossing of a carrier substrate, with positive structural elements arranged irregularly in a grid before their individualization;

[0072] Fig. 7 according to an exemplary embodiment shows a perspective view of a surface of a metastructure blank resulting from the embossing of a carrier substrate, with negative structural elements arranged regularly in a grid, before their individualization;

[0073] Fig. 8A is a flowchart illustrating a first exemplary embodiment of a method for producing a document body, in particular according to Fig. 1A, including a process for producing a metastructure to be integrated into the document body and a subsequent integration of the produced document body as a book page into a book-like document; and

[0074] Fig. 8B is a flowchart illustrating a second exemplary embodiment of a method for producing a document body, in particular according to Fig. 1B.

[0075] Fig. 8C is a flowchart illustrating a third exemplary embodiment of a method for producing a document body, in particular according to Fig. 1C.

[0076] In the figures, identical reference symbols denote identical, similar, or corresponding elements. Elements depicted in the figures are not necessarily shown to scale. Rather, the various elements depicted in the figures are represented in such a way that their function and general purpose are understandable to a person skilled in the art. Connections and couplings between functional units and elements shown in the figures can, unless expressly stated otherwise, also be implemented as indirect connections or couplings. Unless otherwise specified in detail, functional units can, in particular, be implemented as hardware, software, or a combination of hardware and software.

[0077] When the term "step" or "steps" of the procedure is used below, this does not mean that the associated action must necessarily occur in a single, continuous process. Rather, it is also possible that a "step" is composed of several individual processes within a larger procedure and thus corresponds to a sub-process of the procedure.

[0078] Fig. 1A shows, according to a first exemplary embodiment, a layered structure of a document body 1 constructed as a multilayer laminate, in which the individual layers are stacked on top of each other. For the purpose of better identifying the individual layers, however, these are shown largely separately from one another in Fig. 1, whereas in the actual document body they are bonded together by lamination along the stacking direction, so that the document body forms a sheet- or plate-like block.

[0079] Within its interior, the document body 1 contains, as one of its layers, a (first) information carrier layer 2, in or on which a physical representation 3 of information to be represented by the document body 1 is arranged. If the document body 1 is a security document or forms part of one, the information may, in particular, be information requiring protection against forgery, such as, in the case of an identity card, information about the cardholder. Specifically, the information may represent an image, such as a passport photo of the cardholder. The physical representation 3 of the information may, in particular, be formed as a print, engraving, or embossing of the (first) information carrier layer 2, or as a discoloration (e.g., carbonization) of the material of the information carrier layer 2 resulting from the input of energy, in particular laser irradiation (e.g., laser marking, for example, using a gray laser).

[0080] A further layer 4 of the document body 1 is connected to the (first) information carrier layer 2 in such a way that it overlaps, in particular completely, the physical representation 3 of the information. In the overlap area, layer 4 has a metastructure 5, which is either formed within layer 4 itself or (as illustrated in Fig. 1) inserted into a corresponding recess 6 in layer 4. The metastructure 5 is configured such that, when irradiated with light 12 from a defined spectral range, it imparts a multicolored appearance to the information represented by the physical representation 3, based on structural colors generated as a result of the irradiation, without the use of color pigments. In particular, the metastructure can be configured such that, if the information represented by the physical representation 3 contains an image, it imparts a realistic coloring of the image, such as that of a passport photo.The spectral range can correspond in particular to the visible range of the electromagnetic spectrum or to a sub-spectrum of it containing several different colors, especially those required for the aforementioned realistic coloring.

[0081] The core 11 of the document body, formed by layers 2 and 4 including the physical representation 3 and the metastructure 5, can be surrounded on one side or, as shown, on both sides by one or more further layers 7 to 10, each of which also forms a sublayer of the laminate.

[0082] In particular, one or more layers may be present that are configured as a second information carrier layer 7 and carry further information, such as a print or laser marking. For example, in the case of a document body 1 configured as an identification card, this further information may relate to the holder's data, such as name, date of birth, height, etc., while the information displayed by the physical representation 3 relates to an associated image of the identification card holder, which, when illuminated with light according to the spectral range, is colored realistically, at least partially, based on the structural colors generated by the metastructure. "Partially" here can refer in particular to areas of the image and / or to parts of the coloration, e.g., to a true subset of the color components, such as color channels, of the realistic image.

[0083] Further layers 9 and 10 are particularly suitable if they can provide the core of the document body with good protection against undesirable external influences, such as mechanical impacts, moisture, dirt, or aggressive chemical substances. For this purpose, layers 9 and 10 can consist of a polymer material that is largely transparent in the spectral range, such as transparent polycarbonate. Layer 9 can also serve as a carrier layer for a further layer 8, which has spectrally opaque areas and thus acts as a kind of aperture, allowing only partial visibility of the core, but at least a view of the metastructure and, if applicable, of information-carrying areas of layer(s) 7.Overall, the document body 1 is at least sufficiently transparent or partially transparent to light from the spectral range that the metastructure can be illuminated by light 12 from an external environment of the document body 1 in such a way that the representation of the information colored by means of the structural colors generated thereby can be optically perceived by the physical representation 3 from the external environment of the document body 1.

[0084] Each sub-stack of the laminate formed from one or more of the layers 8, 9 and 10 can be interpreted collectively as a cover layer 13, which covers and protects the core 11 of the document body 1 from one side or the other.

[0085] Fig. 1B shows, according to a second exemplary embodiment, a layered structure of a document body 1 constructed as a multilayer laminate, in which the individual layers are stacked on top of each other. For the purpose of better identifying the individual layers, these are again shown largely separately from one another in Fig. 1B, whereas in the actual document body they are bonded together by lamination along the stacking direction, so that the document body forms a sheet- or plate-like block.

[0086] The structure of the document body largely corresponds to that shown in Fig. 1A. However, layer 4, including the insert supporting the metastructure 5 in Fig. 1A, is omitted. Furthermore, the physical representation 3 is no longer separate from the metastructure 5, but rather integrated into it in such a way that the metastructure 5, now formed on or within layer 2, defines both the physical representation and its coloration using structural colors. Color pigments may optionally be present in addition to the partial formation of the physical representation 3.

[0087] Fig. 1C shows, according to a third exemplary embodiment, a layered structure of a document body 1 built as a multilayer laminate, in which the individual layers are stacked on top of each other. For the purpose of better identifying the individual layers, these are again shown largely separately from one another in Fig. 1C, whereas in the actual document body they are bonded together by lamination along the stacking direction, so that the document body forms a sheet- or plate-like block.

[0088] The structure of the document body largely corresponds to that shown in Fig. 1B. In contrast, however, the physical representation, as in the embodiment according to Fig. 1A, is designed as an independent physical component, in particular a color layer, in addition to the metastructure, but integrated together with it in the same layer 2. For this purpose, the physical representation can, for example, be designed as a print on layer 2, and the metastructure can then be added by embossing the printed layer 2.

[0089] Fig. 2 shows the document body 1 from Fig. 1 again in a perspective view, in which the core 11 and an upper cover layer 13 are already depicted as a bonded partial laminate. In fact, in the finished document body 11, the core 11 and one or two cover layers 13 are bonded together by lamination to form a single laminate. The separation between the core 11 and the cover layer 13 shown in Fig. 2 serves only to better illustrate the structure of the document body 1 and the radiation path of the light 12 coming from outside the document body 1 through the cover layer 13 to the metastructure 5 located in the core 11, and the resulting coloring of the information defined by the physical representation 3.

[0090] Fig. 3 shows, according to an exemplary embodiment, a side view of a book-like document 14, in particular a security document, e.g., a passport, which contains one document body 1, e.g., the one from Figs. 1 and 2, as a book page, which, together with any further pages 15, is bound in a book cover 16. The pages 15 and the book cover 16 may be at least partially transparent or have openings through which the metastructure 5 and the physical representation 3 are visible from the outside even when the security document (book) is closed. However, this is only one of many possible variants. In particular, the pages 15 and the book cover 16 may also be completely opaque in the spectral range, so that the metastructure 5 and the physical representation 3 can only be viewed when the book is open and the exposed document body 1 is directly visible.

[0091] Fig. 4 shows an already individualized metastructure 5, which comprises high-refractive-index, dielectric, and / or plasmonic structures with a multitude of structural elements 17 arranged on a plate-shaped support substrate (not shown) and extending orthogonally from it in a stilt-like fashion (and thus "positive") to generate at least a portion of the structural colors. For a given spectral range, the dimensions of the structural elements 17 are chosen such that their respective longest spatial extent and their maximum pairwise distance from the nearest adjacent structural elements in the arrangement are both smaller than the shortest wavelength in the spectral range, allowing local radiation resonances to form within the arrangement. In particular, the longest spatial extent and / or the maximum pairwise distance of the nearest adjacent structural elements can be two micrometers or less.

[0092] The structural elements 17 are arranged on the substrate in such a regular pattern that each element's position corresponds to a grid point in a regular grid. The position of each structural element 17 can be defined as the point resulting from the virtual orthogonal projection of the element's center of mass or geometric center of mass onto the substrate. The shape of the structural elements 17 can and usually will vary across the entire set. This variation, in the grid-like arrangement, is primarily responsible for creating different structural colors depending on the element's position.

[0093] The material of metastructure 5 can be chosen such that, in itself—that is, in the hypothetical absence of the structural elements and the structural colors they produce—it is monochromatic or colorless when irradiated with white light, solely due to the nature of the material. Thus, the inherent color of the material has no, or at least no significant, influence on the coloration of the information, particularly image information, represented by the physical representation 3 through the action of structural colors in metastructure 5. Suitable materials for manufacturing metastructure 5 include, in particular, plastics, metals, metalloids, and dielectric materials.

[0094] Figures 5 to 7 show various exemplary embodiments of a metastructure 5, which can serve in particular as a precursor product of a final, individualized metastructure, referred to herein as a “metastructure blank” 5a, which can be further individualized.

[0095] Fig. 5 shows a section of the surface of a metastructure 5, in particular a metastructure blank 5a, which has a plurality of positive structural elements 17 arranged regularly on a support substrate 18 and which have the same shape. This metastructure blank 5 can serve, in particular, as a precursor product in the sense that it can be adapted to a target color for an information representation to be colored by them via structural color generation, even during a post-processing step in which the shapes of the structural elements are individualized. Such post-processing will be discussed in detail below with reference to the method illustrated in Figure 8.

[0096] Fig. 6 shows another embodiment of a metastructure 5, in particular a metastructure blank 5a, with positive structural elements 17 arranged on a support substrate 18 before their individualization during the aforementioned post-processing. Unlike in Fig. 5, the positions of the structural elements 17 are no longer arranged completely regularly in a continuous grid. Rather, such a regular arrangement exists only in sections, in approximately circular disks or ring-shaped segments of the metastructure blank 5a, resulting in an overall arrangement of concentrically positioned, diverse segments. The sizes, in particular the diameters, of the structural elements 17 also vary from segment to segment.

[0097] Fig. 7 shows a further embodiment of a metastructure 5, in particular a metastructure blank 5a, with a support substrate 18 and structural elements 19 formed as cavities therein, and thus “negative,” before their possible individualization within the framework of the aforementioned post-processing. The arrangement of the negative structural elements again follows a regular grid as an example. As with the positive structural elements 17 from the preceding figures, however, irregular arrangements of various kinds are also conceivable when using negative structural elements 19.

[0098] Fig. 8A shows a flowchart to illustrate a first exemplary embodiment of a method 20 for producing a document body 1, in particular according to Fig. 1A, including a process for producing a metastructure to be integrated into the document body within the framework of the method and a subsequent integration of the produced document body as a book page into a book-like document 14.

[0099] The procedure 20 is divided into several successive sub-processes 21 to 25.

[0100] Subprocess 21 is designed to define and produce a master mold configured as a negative for manufacturing a metastructure blank 5. Subprocess 21 includes a step 26 in which a virtual 3D model of the master mold is created, for example, using a CAD development environment as a 3D CAD model. Based on this model, a corresponding master mold is manufactured as a product in a further step 27. This can be done, in particular, using an additive manufacturing process controlled by the model and / or electron beam lithography on a substrate, especially a plate-shaped one.

[0101] A subsequent subprocess 22 is designed to use the master mold to produce a metastructure blank 5a and to form plasmonic structures on the surface of a substrate blank, in particular a sheet- or plate-shaped support substrate 18. For this purpose, in step 28, the master mold is used as an embossing tool in an embossing process in which the surface of the support substrate is embossed into a surface shape formed as a counterpart to the negative shape of the master mold. This surface shape can be similar to or identical to one of the examples shown in Figures 5 to 7.

[0102] Optionally, the resulting metastructure 5 can be coated with a metallic thin film on the embossed surface in a further step 29. The thin film can serve, in particular, to improve the optical reflectivity of the surface in order to increase the color intensity of the structural colors that can be generated by the metastructure. The thin film can be produced, in particular, by a deposition process suitable given the small structure sizes. A chemical vapor deposition (OVD) process can be used for this purpose.

[0103] Optionally, the thin film can also be sealed in a further step 30 with a protective layer, which can consist in particular of a transparent plastic or lacquer.

[0104] The metastructure 5 is thus produced as a metastructure blank 5a, i.e., up to its subsequent individualization. The sub-process described so far, consisting of sub-processes 21 and 22, is particularly suitable for the efficient production, especially mass production, of metastructure blanks 5a. Specifically, it is sufficient to execute step 26 only once, because the model does not need to be recreated for each master mold. Depending on its mechanical and thermal robustness, the master mold can also be used multiple times for embossing and thus for the production of a plurality of metastructure blanks. The embossing process can also be parallelized when multiple master molds are available.are, in particular, such that in a single embossing process several master forms are used in parallel as embossing tools in order to form a corresponding number of metastructure blanks 5a (or, if no individualization is to be carried out by post-processing, of finished metastructures 5) simultaneously.

[0105] In a further sub-process 23, the document body 1 can now be produced by lamination, including the integration of the metastructure blank 5a resulting from sub-process 22. Specifically, the metastructure blank 5a can be inserted as an insert into a cavity (recess) in a layer 4 in the core 11 of the laminate in step 31. Alternatively, the metastructure blank 5a can itself form a complete layer bearing its imprinted surface structure, which is integrated into the core 11 of the multi-layered document body 1 during lamination.

[0106] In a further step 32, the document body 1 is now joined together by lamination of its layers. The layer structure can correspond in particular to the structure described above with reference to Fig. 1.

[0107] This completes the production of the document body 1 as such, including the metastructure blank 5 integrated within it.

[0108] In a further sub-process 24, the metastructure blank 5a can optionally be individualized into a finished, individualized metastructure 5, in particular by means of a photothermal processing method, such as selective laser irradiation. This allows the structural elements 17 and 19 of the metastructure blank 5a to be individually modified in their shape and / or size, so that the plasmonic and thus optical properties of the surface of the metastructure blank 5a also change. Such processing of the metastructure blank 5a is expediently carried out depending on a predefined target color for the information to be represented by the physical representation 3 and a model that combines the desired target colors with a corresponding shape of the set of structural elements 17 and 19.19 is linked so that, based on the model, control data for a photothermal processing system performing the processing can be derived from the target color, which is then used to control the processing system, e.g., a laser system. Finally, in a further optional subprocess 25, the document body 1, including the integrated and individualized metastructure 5, can be bound as a book page into a book-like document, especially a multi-page, book-like document, such as a passport.

[0109] Fig. 8B shows a flowchart to illustrate a second exemplary embodiment 40 of a method for producing a document body 1, in particular according to Fig. 1B, including a process for producing a metastructure to be integrated into the document body within the framework of the method and a subsequent integration of the produced document body as a book page into a book-like document 14.

[0110] Method 40 largely corresponds to method 20 from Fig. 8A, but with the following differences: The production or insertion of layer 4 (including the insert supporting metastructure 5 in Fig. 1A) in the layer structure of the document body is omitted. Furthermore, the physical representation 3 is no longer formed separately from the metastructure 5, but rather integrated into it in such a way that the metastructure 5, which is now formed on or in layer 2, defines both the physical representation and its coloration using structural colors. The production processes for the metastructure and the physical representation thus coincide, at least partially. Color pigments can optionally be used in addition to the partial formation of the physical representation 3, for example, within a printing process. Sub-process 23 from Fig.8A is thus modified to a sub-process 41 in that the production of the document body 1 by lamination 43 includes the insertion 42 of the metastructure blank, which also contains the physical representation 3.

[0111] Fig. 8C shows a flowchart to illustrate a third exemplary embodiment 50 of a method for producing a document body 1, in particular according to Fig. 1C, including a process for producing a metastructure to be integrated into the document body within the framework of the method and a subsequent integration of the produced document body as a book page into a book-like document 14.

[0112] Method 50 largely corresponds to method 40 from Fig. 8B, except that the metastructure 5 does not simultaneously provide the physical representation 3, but is formed separately from it, though in the same layer 2. The physical representation is thus formed, at least partially, not by the metastructure, but independently of it, for example in process step 52 by using color pigments (e.g., by printing) or by laser processing. Here, the metastructure 5 again serves to color the information represented by the physical representation 3 for the viewer using structural colors. Subprocess 22 from Fig. 8B is thus modified to subprocess 51 by additionally including the aforementioned process step 52.

[0113] REFERENCE MARK LIST

[0114] 1 Document body

[0115] 2 first information carrier layer

[0116] 3. Physical representation of information

[0117] 4, 8-10 further layers of the document body

[0118] 5 Metastructure

[0119] 5a Metastructure blank

[0120] 6 Exclusion

[0121] 7 second information carrier layer

[0122] 11 core

[0123] 12 lights

[0124] 13 Top layer

[0125] 14 book-like documents

[0126] 15 book pages

[0127] 16 Book cover

[0128] 17 positive structural elements

[0129] 18 Carrier substrate

[0130] 19 negative structural elements

[0131] 20 Method, first embodiment

[0132] 21-32 Sub-processes and steps of the procedure 20

[0133] 40 Method, second embodiment

[0134] 41-43 compared to procedure 20 supplemented or modified sub-processes

[0135] 50 Methods, third embodiment

[0136] 51-52 compared to procedure 40 supplemented or modified sub-processes or process steps

Claims

REQUIREMENTS 1. Document body (1), in particular for a security document, comprising within it: an optically detectable physical representation (3) of information; and a metastructure (5) configured such that, when irradiated with light (12) from a defined spectral range, it gives the information represented by the physical representation (3) a multicolored appearance by means of structural colors generated as a result of the irradiation; wherein the document body (1) is at least transparent or partially transparent to the light (12) from the spectral range such that the metastructure (5) can be illuminated with the light (12) from an external environment of the document body (1) in such a way that the representation of the information colored by means of the structural colors generated thereby becomes optically detectable from the external environment of the document body (1).

2. Document body (1) according to claim 1, wherein the physical representation (3) of the information is designed such that a representation of the information can be optically detected from the outer environment of the document body (1) as soon as the metastructure (5) is irradiated with diffuse radiation from the spectral range.

3. Document body (1) according to one of the preceding claims, wherein the metastructure (5) comprises a support substrate (18) in or on which high refractive index dielectric and / or plasmonic structures are arranged for at least partial generation of the structural colors.

4. Document body (1) according to one of the preceding claims, wherein the set of dielectric and / or plasmonic structures in at least one section of the metastructure (5) comprises an arrangement of a plurality of positive and / or negative structural elements (17, 19) whose respective longest spatial extent and whose pairwise greatest mutual distance of nearest neighboring structures in the arrangement are both less than the smallest wavelength from the spectral range, so that local radiation resonances can form in the arrangement.

5. Document body (1) according to claim 4, wherein the longest spatial extent and / or the pairwise greatest mutual distance is nearest The distance between adjacent structures is at most two micrometers, in particular at most one micrometer.

6. Document body (1) according to claim 4 or 5, wherein in the section the arrangement of the structural elements (17, 19) of the plurality is designed in such a regular manner that the positions of the structural elements (17, 19) in the section each correspond to a grid point of a grid.

7. Document body (1) according to one of claims 4 to 6, wherein the arrangement of the structural elements (17, 19) is designed such that the coloring of the output radiation caused by the structural colors is color-stable over a radiation angle range of at least 90°± 30°, in particular at least 90°± 45°, to such an extent that the wavelengths of the colors involved in the coloring do not change by more than 50%, wherein an angle of 90° corresponds to a top view orthogonal to a surface supporting the micro- or nanostructure.

8. Document body (1) according to one of the preceding claims, wherein the metastructure (5) is made of a material or a combination of several materials which, in the imagined absence of the structural elements (17, 19) and the structural colors thereby elicited, is monochromatic or colorless when irradiated with white light (12) solely due to the material.

9. Document body (1) according to one of the preceding claims, wherein the metastructure (5), based on the amount of material, contains one or more of the following materials individually or cumulatively predominantly: plastic, metal, semi-metal, dielectric material.

10. Document body (1) according to claim 11, wherein the metastructure (5), based on the amount of material, contains one or more of the following materials individually or cumulatively predominantly: aluminium, germanium, gold, silver, silicon, titanium.

11. Document body (1) according to one of the preceding claims, wherein the document body (1) comprises a multilayer laminate in the interior of which the metastructure (5) is embedded.

12. Document body (1) according to claim 11, wherein the metastructure (5) is embedded at least sectionally as an insert in at least one layer (4) of the laminate.

13. Document body (1) according to claim 11 or 12, wherein the metastructure (5) is embossed at least section by section into a layer of the laminate.

14. Document body (1) according to one of claims 11 to 13, wherein the physical representation (3) and the metastructure (5) are integrally formed in the same layer of the laminate.

15. Document body (1) according to one of claims 11 to 13, wherein the metastructure (5) is configured such that it itself provides both the optically detectable physical representation and generates the structural colors as a result of irradiation.

16. Document body (1) according to one of claims 11 to 13, wherein the physical representation (3) is formed in a first layer of the laminate and the metastructure (5) is formed in a second layer of the laminate different from the first layer.

17. Security document comprising a document body (1) according to any of the preceding claims.

18. Method (20) for producing a metastructure (5) configured to be integrated into the interior of the document body (1) according to any one of claims 1 to 16 and to generate structural colors when irradiated with polychrome electromagnetic radiation from at least one spectral range of the electromagnetic spectrum, wherein the method (20) comprises: Generating (21) a master form as a negative for generating a surface structure of the metastructure (5) within the framework of a subsequent embossing process (28) using the master form as at least a partial embossing tool; and Using the embossing tool having the master form to process a plate- or sheet-shaped support substrate by means of the embossing process (28) in order to emboss the metastructure (5) in the support substrate in such a way to develop such that the master form defines the shaping of the metastructure (5) at least partially.

19. Method (20) according to claim 18, wherein the master form is or is defined such that, in conjunction with the embossing process (28), it defines a plurality of positive and / or negative structural elements (17, 19) of the metastructure (5) to be produced, which, in their interaction when irradiated with light (12) from the defined spectral range, produce the structural colors at least partially.

20. Method (20) according to claim 18 or 19, wherein the production (21) of the master form is carried out at least partially using an additive manufacturing process (27) controlled depending on a virtual 3D model of the master form to be produced.

21. Method (20) according to claim 17 or 18, wherein the production (21) of the master form is carried out at least partially by applying electron beam lithography to a support substrate.

22. Method (20) according to one of claims 18 to 21, further comprising: applying a metallic thin film to the metastructure (5) formed from the support substrate during the embossing process.

23. Method (20) according to one of claims 18 to 21, further comprising: applying a metallic thin film to the substrate prior to processing it by means of the embossing process.

24. Method (20) according to one of claims 18 to 23 further comprising: at least partial sealing (30) of a surface of the metastructure (5) created by the embossing process (28) using the master form with respect to its shape, with a protective layer containing lacquer and / or plastic.

25. Method (20) for producing a document body (1) according to any one of claims 1 to 16, wherein a metastructure (5) obtainable by the method (20) according to any one of claims 18 to 24 is integrated into the interior of the document body (1) such that the metastructure (5) is visible from an external environment of the document body (1) to the light (12) It is possible to illuminate that the representation of the information colored by means of the structural colors generated thereby becomes optically perceptible from the outer environment of the document body (1).

26. Method (20) according to claim 25, wherein the metastructure (5) arranged inside the document body (1) is produced using a photothermal Method which acts on the document body (1) from its environment, is processed (24) and modified in such a way that a change in the coloring of the information represented by the physical representation (3) is produced by the structural colors under the same irradiation from the spectral range.

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