EP3317111B1 - Security element with colour-filtering grating - Google Patents

Description

The invention relates to a security element for a document of value, wherein the security element has a two-dimensionally regular pattern of individual cylindrical surface elements of high-refractive, in particular metallic material, which lie in a lattice plane, are spaced apart by gaps and are embedded on all sides in a dielectric, wherein the regular Pattern in at least two directions parallel to the lattice plane has a periodicity of 100 nm to 800 nm, preferably 200 nm to 500 nm.

The invention further relates to a method for producing a security element for a document of value, wherein a two-dimensionally regular pattern of individual cylindrical surface elements of high refractive, in particular metallic material is formed, which lie in a lattice plane, are spaced apart by gaps and are embedded on all sides in a dielectric wherein the regular pattern in at least two directions parallel to the lattice plane has a periodicity of 100 nm to 800 nm, preferably 200 nm to 500 nm.

The invention also relates to a not yet executable precursor to a document of value.

Such a security element or method for producing as well as a non-executable precursor to a value document are known from the WO 2012/156049 A1 , which discloses a security element according to the preamble of claim 1, known. There are more references to the state of the art with regard to subwavelength gratings. This generic security element has good color filter properties and can be in multiply an embossing process cost-effectively. The security element provides an array of surface elements, also referred to as nanodisks because of their size, arranged above a base surface having a complementary hole pattern. This hole pattern is also referred to as a nanohole array. For the production, usually a structure is embossed in a dielectric which is to surround the nanodisks and nanoholes. The color effect, especially in transmission, depends very much on the distance between the nanodisks and the nanoholes. This distance is determined by the height of the embossed structure and thus ultimately by an embossing tool. During the embossing process, in particular due to wear of the embossing tool, fluctuations or a continuous decrease in the embossing height over the production period occur. This causes effort, in particular a frequent embossing tool exchange in series production, to ensure a constant color effect. The WO 2011/107782 A1 relates to a Moire Magnifier whose pixels are in the grid 1-100 microns.

The invention is therefore based on the object of specifying a two-dimensional, color-filtering grating, which on the one hand has a good color filter property and on the other hand can be produced by inexpensive duplication methods.

This object is achieved by security element for a document of value, wherein the security element has a two-dimensional regular pattern of individual cylindrical surface elements of high refractive, in particular metallic material, which lie in a lattice plane, are spaced apart by gaps and are embedded on all sides in a dielectric, wherein the regular pattern in at least two directions, which run parallel to the lattice plane, has a periodicity of 100 nm to 800 nm, preferably of 200 nm to 500 nm, wherein the gaps between the surface elements in a range of at least 1 micron, optionally 5 microns to 50 microns, perpendicular to the lattice plane also only have dielectric.

The object is further achieved by a method for producing a security element for a document of value, wherein a two-dimensionally regular pattern of individual cylindrical surface elements of high-refractive, in particular metallic material is formed, which lie in a lattice plane, are spaced apart by gaps and all sides in one Dielectric embedded, wherein the regular pattern in at least two directions, which extend parallel to the lattice plane, a periodicity of 100 nm to 800 nm, preferably from 200 nm to 500 nm, wherein the gaps between the surface elements in a range of at least 1 micron , optionally 5 microns to 50 microns, perpendicular to the lattice plane also have only one dielectric, in particular seen perpendicular to the lattice plane are not covered by high refractive index material.

The object is finally also solved by a non-executable precursor to a value document containing a security element according to the invention.

The grid provides high-refractive surface elements that are different than in the WO 2012/156049 A1 are no longer arranged over a high-refractive base layer. Rather, there are also the gaps between the surface elements in a range of at least 1 micron (depending on the realization up to 50 microns or more) of dielectric, non-high refractive index material. The area is measured perpendicular to the plane in which the surface elements are located, and extends on both sides of the plane. For the optical effect of the security element no longer depends on a precise distance of the high refractive surface elements to a high refractive base layer. As a result, an embossing depth no longer plays a role in the production process, and the abovementioned wear problem of the embossing tool is avoided.

The high refractive property of the surface elements is achieved by a suitable choice of material. In addition to metal as a material are in particular silicon, zinc sulfide or titanium dioxide in question. In this description, the term "metallic" is taken as an example of "high refractive index", unless expressly described otherwise.

For the dielectric material, which z. B. has a refractive index of about 1.5, are particularly suitable plastic films, for. As PET films, as a substrate. The actual basic structure is z. B. also in plastic, preferably UV lacquer is formed. After evaporation, the structure is finally filled with UV varnish and laminated with a cover film. Thus, there is a layer structure in which the top and the bottom has substantially the same refractive index.

Furthermore, the high refractive index material of the surface elements is not limited to simple metallic layers. There are also multiple layers, especially trilayer conceivable. It is known that multi-coated one-dimensional periodic gratings enable strong color filter filtering through the formation of Fabry-Perot resonators both in reflection and in transmission. In trilayer, the following layers are particularly preferred: two semi-transparent metal layers with an intervening dielectric spacer layer or two high-index layers with an intermediate low-refractive layer. For the Metal layers are the following materials: Al, Ag, Pt, Pd, Au, Cu, Cr and alloys thereof. Suitable high-index layers are, for example, ZnS, ZnO, TiO ₂ , ZnSe, SiO ₂ , Ta ₂ O ₅ or silicon. SiO ₂ , Al ₂ O ₃ or MgF _{2 are} suitable as low-index layers.

The refractive index of the dielectric, which fills the gaps between the surface elements, may for example be between 1.4 and 1.6.

The color effects depend primarily on the periodicity of the pattern. The color can also be varied by the geometry of the nanodisks. This can be exploited to create colored symbols or images. For this purpose, the surface filling factor and / or the geometry of the surface elements and / or their material can be locally varied. In particular, it is possible to make groups of several surface elements with identical dimensions so that a desired color effect occurs. A group then forms a subpixel. Several subpixels are designed with different color properties by appropriate geometric design and then combined into one pixel. This allows a colored image representation. The different colors can be varied by the corresponding local variation of one or more of the parameters of the grid.

Due to the pixel-by-pixel color mixture of basic colors, eg. RGB colors, in subpixel areas true color images can be made. The advantage of such structures over the conventional printing technique is that in this case a very fine structuring down to the micrometer range can be made. This fine structuring is particularly suitable for applications in Moire magnification arrangements, z. By forming the grating so as to form microimages for moiré magnification arrangements provides. In microlens arrays, the large angular tolerance of the two-dimensionally periodic gratings described above has a very favorable effect, since the microlenses have a small focal length with a relatively large aperture ratio in moiré magnification arrangements. Therefore, the structures described herein show greater color saturation in combination with microlenses than previously known one-dimensional periodic sub-wavelength structures.

Characteristic of the security element is that opposite to the WO 2012/0156049 A1 Known approach the base layer of high refractive index material is missing, since the gaps between the surface elements (the latter in the above range) are formed by a dielectric material. It is not mandatory that it is consistently the same dielectric. What is essential is the refractive index difference between the surface elements and the dielectric material or materials in the gaps and in the vicinity of the surface elements. Particularly preferred is a security element whose gaps seen perpendicular to the ground plane are not covered by high refractive index material.

The security element may in particular be integrated in a security thread, tear-open thread, security strip, security strip, patch or label. In particular, the security element can span transparent areas or recesses.

The security element can in particular be part of a not yet executable precursor to a value document, which additionally may have further authenticity features. By value documents on the one hand documents are understood, which with the security element are provided. On the other hand, value documents can also be other documents or objects that are provided with the security element, so that the value documents have non-copyable authenticity features in order to enable authenticity verification and to prevent undesired copies. Chip or security cards, such as bank or credit cards or ID cards, are further examples of a value document.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the specified combinations but also in other combinations or alone, without departing from the scope of the present invention.

Fig. 1

eine perspektivische Schemadarstellung einer ersten Ausfüh-rungsform eines Sicherheitselementes,

Fig. 2

eine Abwandlung des Sicherheitselementes der Fig. 1,

Fig. 3

eine weitere Abwandlung des Sicherheitselementes der Fig. 2,

Fig. 4-7

Diagramme hinsichtlich der Filtereigenschaften verschiedener Sicherheitselemente,

Fig. 8-9

Schemadarstellungen zur Ausbildung des Sicherheitselementes zur Bilddarstellung,

Fig. 10-11

Schemadarstellungen verschiedener Herstellungsstufen des Sicherheitselementes für verschiedene Herstelltechniken, und

Fig. 12

ein Sicherheitselement mit einem weiteren Sicherheitsmerkmal.

The invention will be explained in more detail by way of example with reference to the accompanying drawings, which also disclose features essential to the invention. Show it:

Fig. 1

a perspective schematic representation of a first embodiment of a security element,

Fig. 2

a modification of the security element of Fig. 1 .

Fig. 3

a further modification of the security element of Fig. 2 .

Fig. 4-7

Diagrams regarding the filter characteristics of different security elements,

Fig. 8-9

Schematic representations for the formation of the security element for image presentation,

Fig. 10-11

Schematic representations of different manufacturing stages of the security element for different manufacturing techniques, and

Fig. 12

a security element with another security feature.

Fig. 1 shows a schematic representation of a security element 1. It has on a support 2 surface elements 3. There are gaps 4 between the surface elements 3. The carrier 2 is made of a dielectric material, the surface elements of a high refractive index material, for example a metallic coating. The surface elements 3 are covered with a cover layer 5, so that they are surrounded on all sides by dielectric. The arrangement of the surface elements 3 with the intervening gaps 4 forms a pattern 6, so that a total of a two-dimensional periodic sub-wavelength grating is formed by the periodic arrangement of surface elements. The surface elements 3 consist of a high refractive index material with a refractive index v. Due to the arrangement and the embedding in dielectric with the refractive index n (in the embodiment according to FIG Fig. 1 the refractive indices of the carrier 2 and the cover layer 5 are identical; this is not mandatory) results for incident radiation E a color effect for transmitted radiation T and reflected radiation R. This will be explained below, as well, that the color effect of an angle of incidence Θ to the surface normal, here registered as an optical axis OA depends.

The shape of the surface elements 3 can be designed differently. Fig. 2 shows an embodiment with in plan view circular surface elements. In general, the surface elements 3 are cylindrical (not necessarily circular cylindrical) and have a width w ₁ and a depth w ₂ . The arrangement of the surface elements 3 in the pattern 6 is periodic. Fig. 1 and Fig. 2 show a period d. It may be different in other embodiments in the two spatial directions of the basic or lattice plane 7.

With regard to the geometry of the surface elements 3, which form nanodisks, intermediate forms between a circular and square plan are also possible. A symmetrical shape has particularly good color filtering for unpolarized light. In particular, squares with rounded corners are suitable for the practical implementation.

If the security element 1 is incident at the angle Θ radiation E, the reflection R in the glancing angle shows the zeroth order of diffraction and, at the same time, a zeroth diffraction order in transmission. The structure of the surface elements 3, so the nanodisks is not limited to homogeneous, metallic or semi-metallic layers. There are also multi-layers, especially so-called trilayer conceivable, for example, show a color shift effect.

It is known that multi-coated, one-dimensionally periodic gratings enable strong color filter filtering through the formation of Fabry-Perot resonators both in reflection and in transmission. In trilayer, the following layers are particularly preferred: two semi-transparent metal layers with an intervening dielectric spacer layer or two high-index layers with an intermediate low-refractive layer. The following materials are suitable for the metal layers: Al, Ag, Pt, Pd, Au, Cu, Cr and alloys thereof. Suitable high-index layers are, for example, ZnS, ZnO, TiO ₂ , ZnSe, SiO ₂ , Ta ₂ O ₅ or silicon. SiO ₂ , Al ₂ O ₃ or MgF _{2 are} suitable as low-index layers.

The periodicity d lies in the sub-wavelength range, ie in the range between 100 nm and 800 nm, preferably between 200 nm and 450 nm or 600 nm. The fill factors u ₁ / d ₁ and u ₂ / d ₂ are between 0.2 and 0.8 , preferably between 0.3 and 0.7. In order to achieve polarization-independent color filtering, the profile parameters for the two spatial directions are chosen to be as identical as possible, ie w ₁ = w ₂ . This is optional. Likewise, in the described embodiment, the periodicity directions are perpendicular to each other. This too is optional. Also spatially asymmetrical arrangements of the profile and the periodicity are conceivable. In other words, the pattern 6 does not have to, as in Fig. 1 shown to be a Cartesian pattern.

Fig. 2 shows a security element 1, the surface elements 3 are formed circular-cylindrical. This form is suitable as the construction of the Fig. 1 or 2 especially for color filters for unpolarized light. Other mathematically cylindrical geometries are provided for the surface elements in embodiments. For example, variations of the square shape are the Fig. 1 or the circular shape of the Fig. 2 provided, z. B. by rounded corners.

Depending on the variation of the grating period and the fill factor, different saturated colors result in reflection and transmission, in particular for fill factors above 0.35 and especially above 0.45. Exemplary parameters of such structures are summarized in Table 1 below. The shape of the surface elements (nanodisks) is substantially cuboid with a uniform side length w and the height t, in the cases discussed below exemplary for t = 80 nm. Table 1: Parameters of security elements 1 structure d [nm] w [nm] fill factor a) 242 162 0.67 b) 261 173 0.7 c) 281 184 0.65 d) 320 219 0.68 e) 362 250 0.69

All lattices listed above were formed on PET films in UV lacquer, provided only in the wells with an 80 nm thick aluminum layer and then laminated with a PET film. The refractive index of the PET film and the UV varnish is about 1.56 in the visible.

Fig. 4 shows the measured transmission (on the vertical axis) at normal incidence of light Θ = 0 ° for the safety element of Table 1 for different wavelengths (on the transverse axis in nm). These security elements have different periods at about the same filling factor w / d. The transmission spectra show a resonant minimum, which is shifted into the long-wave range for increasing periods. In order to reflect the color impression of a viewer, the color properties of these security elements in the CIE 1931 color space were examined. For this purpose, the transmission spectra were folded with the emission curve of a standard D65 lamp and the sensitivity of the human eye and from this the color coordinates X, Y, Z were calculated. The D65 lighting corresponds approximately to the daylight. The X, Y, Z coordinates were then normalized and finally the color coordinates x and y are obtained. These values can be directly attributed to the human perception of the color perception of a viewer. Fig. 4b shows the calculated color values in CIE 1931 color space. The white point is marked with the symbol "O". The triangle limits the color range, which can usually be displayed with screens. The diagram shows the x, y color coordinates as trajectories. It turns out that a large color range can be realized by varying the period.

The angular dependence of the colors in transmission are exemplarily demonstrated for the structure (c) with the period d = 281 nm. Fig. 5b shows three transmission spectra at the angles of incidence Θ = 0 °, 15 ° and 30 °. Here it is characteristic that when tilting no shift of the minimum occurs. The calculated color values of the Fig. 5b x, y demonstrate that the color is barely changed by the tilt, only the color saturation decreases for increasing angles. In addition, the brightness L * was calculated from the color coordinates X, Y, Z, which corresponds approximately to the intensity perceived by the viewer. The brightness L * here is about 25 and is almost constant for an angle change from 0 ° to 30 °.

The reflection of the security element 1 shows Fig. 6a in (non-normalized) values as a function of wavelength. This shows that these spectra each contain a pronounced resonant maximum whose position approximately corresponds to the position of the minima of the transmission spectra. These spectra were also converted to the x, y color values shown in the CIE 1931 color diagram of Fig. 6b are shown. By the illustrated security element red, yellow and green shades can be generated. For blue or violet colors (not shown), a grating period of the nanodisk arrays <240 nm must be selected.

The color consistency in a variation shows Fig. 7a as spectral reflection of the security element (c) of Table 1 for the angles Θ = 0 °, 15 ° and 30 °. The From this calculated color values x, y demonstrate that the hue in reflection is hardly changed by the change of the angle of incidence. However, the color saturation becomes weaker for increasing angles Θ.

The geometry-dependent coloring described above can be used to create colored symbols or images. Fig. 8a and b show three regions of different geometry (d _R , w _R ), (d _G , w _G ) and (d _B , w _B ) of the pattern 6, which appear in the colors red, green and blue. These different colors can be caused by the corresponding variation of one or more profile parameters. The three regions 11, 12, 13 correspond to RGB subpixels and together form a pixel 14. In each region 11, 12, 13, the respective geometry ensures that the corresponding colors red, green and blue are effected. At the same time, the proportion of the color of the respective RGB subpixel in the pixel 14 can be set by the choice of geometry. Thus, the pixel 14 can be given a desired color. The color mixing of the primary colors effected in the pixel 16 by the regions 11, 12, 13 of the RGB subpixels thus makes true color images possible. The advantage of such a structure over a conventional printing technique is that a very fine structuring down to the micrometer range is possible, which is advantageous in particular with magnification arrangements. The security element 8a, b according to Fig. 12 allows micro images in which the pattern changes laterally to achieve a color or an intensity contrast in the microimage. The structure described here is preferred for this, since their optical properties are very angle-tolerant, ie their color hardly changes with a variation of the angle of incidence. This property is advantageous in a combination with microlens arrays, since the light perceived by a viewer comes from different light paths, which have different angles of incidence.

The intensity in the individual color pixels can be adjusted via the area ratios of the nanodisk arrays to surrounding unstructured areas. The unstructured areas are either completely metallized or completely transparent and appear neutral in color. This lateral arrangement of a region filled with a nanodisk array in the vicinity of an unstructured region can also serve to form a motif against a color-neutral background.

Fig. 9 shows side by side different patterns 6 of the nanodisks, which are arranged orthogonally or hexagonally. The individual nanodisks can have different geometries such as squares, rectangles, circles, ellipses or triangles. Such a lateral variation of the arrangement can also produce a variation in the color. In addition to the hexagonal arrangement, other arrangements such as octagonal arrangements are possible, as in Figure 9 illustrated.

The security element 1 can be combined with other embossing structures such as holograms, micromirror arrangements and known subwavelength structures for the production of security features. On the one hand, this increases the counterfeiting security of such features. In addition, safety features can be visually upgraded by the color attractiveness of the nanodisk arrays described here. The nanodisk arrays described here are particularly suitable for see-through elements, as they show colors in reflection and in transmission. An additional security against forgery of this structure is provided by the first diffraction order, which is observable for grating periods of approximately> 330 nm at an oblique angle of incidence.

The security element 1 can be produced by a dielectric having two-dimensionally periodically arranged recesses according to the pattern 6 is vapor-deposited vertically with high refractive index material, for example one of said metals or metal alloys. Then a coating with holes on the upper level is created. In addition, the bottoms of the periodically arranged depressions are coated in a high-refractive index and form the nanodisk array, ie the pattern 6 of the surface elements 3. The top metallic hole structure can then be removed by known methods so that the pattern 6 of the surface elements 3 remains in the depressions , A carrier treated in this way can subsequently be embedded in a dielectric or laminated with a cover film. For this purpose, preference is given to using a photopolymer which has the same refractive index as possible, ideally even the same refractive index as the carrier material into which the depressions have been embossed.

The 10a and 10b show two different stages during this manufacturing process. Fig. 10a shows the carrier 15, in which the recesses 16 have been introduced in the arrangement according to the pattern 6, for example by an embossing process in an embossable medium of the carrier 15, for example an embossing lacquer which is part of the carrier 15. Subsequently, the coating 17 was applied, which in Fig. 10a hatched is registered. Fig. 10b shows the subsequent state after the removal of the coating 17 on the upper side 18 of the carrier 15, ie at all portions except the depressions 16. The high refractive coating, such as metallization, thus remains exclusively in the depressions 16 and forms the surface elements 3. The top 18th is now without coating 17.

The original for the production of an embossing tool, which is used in the stamping process according to 10a and 10b can be used, for example, photolithographically getting produced. This can be done using an e-beam system, focused ion beam or interference lithography. The written in photoresist structure is then developed, while the photoresist partially removed. The resulting structure is then preferably etched into a quartz wafer so that as far as possible vertical flanks of the profile are formed. The quartz mask can now be copied eg in Ormocer or replicated by galvanic impressions. It is also a direct impression of the photolithographically produced original in Ormocer or nickel in a galvanic process conceivable. To produce a stamping cylinder, the original structure often has to be joined together on one level and finally galvanically molded. This galvanic impression can then be clamped onto a cylinder and used as embossing cylinder. Starting from such an embossing master, the structure can now be replicated in UV varnish on film, eg PET film. The thus structured films are then directed under high vacuum with the desired coating evaporated. So that the combination of a nanodisk array and a nanohole array is formed (see Fig. 10a ), from which the coating 17 with the nanohole arrays is removed again.

The generation of the sub-waveguide structure of the surface elements 3 according to the pattern 6 is also possible with a transfer method. For this purpose, an intermediate carrier 19 is embossed so that it has elevations 20, which are arranged according to the pattern 6. The embossing process is essentially the same as that of the 10a and 10b However, the embossing tool for this manufacturing technique is negative to that of 10a and 10b educated. The intermediate carrier 19 embossed in this way is then provided with the coating 17, so that, as a result, a coating also remains on the elevations 20. This coating is then combined with a Metal transfer method, as it is, for example, from the DE 102012018774 A1 or DE 102013005839 A1 is known, transferred to the carrier 15, optionally by using an intermediate transfer to another temporary carrier. The carrier 15 thus provided with the pattern 6 of the surface elements 3 is then coated or laminated with a dielectric in the form of the cover layer 5.

A further production method (not shown in the figures) provides directly for a structuring of a metal layer 17 on the still planar carrier 5, for example by a photolithographic etching process or ablation with laser irradiation.

The security element according to the invention can be combined with other security elements. An example of this shows the Fig. 12 , which provides an area II, in which the security element 1 according to the invention is formed and a region I with a further security element 21, for example, the construction according to WO 2012/156049 A1 equivalent. This can for example be made particularly simple by the fact that in the region II, the coating 17 in the manufacturing process according to Fig. 10a, 10b not removed. The areas I and II or the security elements 21 and 1 then show different colors with otherwise identical geometry of the pattern 6. In particular, the front and back of the area I appear differently in reflection, while the reflection of the front and back of the area II identical is.

Of course, in the above description, the term "about" or "below" is to be understood as exemplary only and with reference to the representation in the drawings. Of course, the structure can also be inverted to that effect.

LIST OF REFERENCE NUMBERS

1.21

security element

2

carrier

3

surface element

4

gap

5

topcoat

6

template

7

Basic or lattice plane

8, 9, 10

layer

11, 12, 13

Area

14

pixel

15

carrier

16

deepening

17

coating

18

top

19

subcarrier

20

increases

I, II

Area

t

coating thickness

w ₁

width

w ₂

depth

d

period

e

incident radiation

R

reflected radiation

T

transmitted radiation

OA

optical axis

Θ

corner

Claims (13)

1. Security element for a valuable document, wherein the security element (1) comprises a two-dimensionally regular pattern (6) made of individual cylindrical surface elements (3) made of a highly refractive, in particular metallic, material, which surface elements (3) are located in a grating plane (7), are spaced apart from one another by gaps (4) and are embedded on all sides in a dielectric (2, 5), wherein the regular pattern (6) has a periodicity (d) of 100 nm to 800 nm, preferably from 200 nm to 500 nm, in at least two directions that extend parallel to the grating plane,
   characterized in that the gaps (4) between the surface elements (3) likewise comprise only dielectric (2, 5) in a region of at least 1 µm perpendicularly to the grating plane (7).
2. Security element according to Claim 1, characterized in that the gaps (4) between the surface elements (3), viewed perpendicularly to the grating plane (7), are not covered by highly refractive material.
3. Security element according to Claim 1 or 2, characterized in that the surface elements (9) comprise a material that contains: Al, Ag, Cu, Cr, Si, Zn, Ti, Pt, Pd, Ta and an alloy thereof.
4. Security element according to one of the above claims, characterized in that the dielectric (2, 5) has a refractive index of between 1.4 and 1.6.
5. Security element according to one of the above claims, characterized in that the regular pattern (6) of the surface elements (3) has an area fill factor of 0.15 to 0.85, preferably of 0.35 to 0.8.
6. Security element according to one of the above claims, characterized in that at least one of the following parameters of the pattern (6) locally varies for producing coloured image information: area fill factor, the period (d), dimensions of the surface elements (3) and the highly refractive material of the surface elements (3).
7. Security element according to one of the above claims, characterized in that the surface elements (3) have a multilayer construction (8, 9, 10), in particular in the form of a colour shift layer system.
8. Precursor, not yet fit for circulation, of a valuable document having a security element (1) according to one of the above claims.
9. Precursor according to Claim 8, characterized in that the security element (1) spans transparent regions or cutouts.
10. Method for producing a security element (1) for a valuable document, wherein a two-dimensionally regular pattern (6) is formed from individual cylindrical surface elements (3) made of a highly refractive, in particular metallic, material, which surface elements (3) are located in a grating plane (7), are spaced apart from one another by gaps (4) and are embedded on all sides in a dielectric (2, 5), wherein the regular pattern (6) has a periodicity (d) from 100 nm to 800 nm, preferably from 200 nm to 500 nm, in at least two directions that extend parallel to the grating plane (7),
    characterized in that the gaps (4) between the surface elements (3) likewise comprise only a dielectric (2, 5) in a region of at least 1 µm perpendicularly to the grating plane (7), and are not covered by highly refractive material, in particular viewed perpendicularly to the grating plane (7).
11. Method according to Claim 10, characterized in that a security element (1) according to one of Claims 1 to 7 is produced.
12. Method according to one of Claims 10 and 11, characterized in that depressions (16) that are arranged as per the regular pattern (6) and have the geometry of the surface elements (3) are formed, in particular embossed, in a carrier (R) that comprises the dielectric, in that the carrier (R) is coated with the highly refractive material of the surface elements (3), in that the coating (17) is removed again outside the depressions (16), and in that the carrier (R) and the surface elements (3) are then covered with a cover layer comprising the dielectric.
13. Method according to one of Claims 10 and 11, characterized in that elevations (20) that are arranged as per the regular pattern (6) and have, in plan view, the geometry of the surface elements (3) are formed on an intermediate carrier (19), in that the intermediate carrier (19) is coated with the highly refractive material of the surface elements (3), in that elevated portions of the coating (17) are transferred, in a contact transfer step, to a carrier (R) comprising the dielectric, and in that the carrier (R) and the surface elements (3) are covered with a cover layer comprising the dielectric.

Images