DE102014016009A1 - Method for producing a security element with a lenticular image - Google Patents

Abstract

The invention relates to a method for producing a security element having a lenticular image (70) for displaying one or more target images (18A, 18B) visible only from predetermined viewing directions, their motifs (22A, 22B) by visually recognizable, contrasting metallic subregions and demetallized subregions (42A, 42B) of a motif layer (40) are formed, wherein in the method - a lenticular image (70) is provided with a lenticular of a plurality of microlenses (34) and spaced from the lenticular metallic Motive layer (40), a pulsed laser radiation in the beam path between the laser source (52) and the lenticular image (70) by a beam former (60) or a switchable mask (82) having a motif-shaped beam cross-section is provided, and - a plurality of microlenses (34) de s lenticular grid is acted upon simultaneously with the laser beam with the motif-shaped beam cross-section (62) to simultaneously produce a plurality of partially motive demetallisierter portions (42, 42 B) in the underlying metallic motif layer (40).

Description

The invention relates to a method for producing a security element with a lenticular image for displaying one or more target images visible only from predetermined viewing directions, wherein the motifs of the target images are formed, in particular, by visually discernible, contrasting metallic and demetallized portions of a motif layer.

Data carriers, such as valuables or identity documents, but also other valuables, such as branded goods, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction.

Security elements with viewing-angle-dependent effects play a special role in the authentication of authenticity since they can not be reproduced even with the most modern copiers. The security elements are thereby equipped with optically variable elements that give the viewer a different image impression under different viewing angles and, for example, show a different color or brightness impression and / or another graphic motif depending on the viewing angle.

For example, ID cards such as credit cards or identity cards have long been personalized by laser engraving. In personalization by laser engraving, the optical properties of the substrate material are irreversibly changed by suitable guidance of a laser beam in the form of a desired marking.

The publication EP 0 219 012 A1 describes a badge with a partial lenticular structure. This lens structure inscribes information into the card at different angles with a laser. This information can then be detected only at this angle, so that when tilting the map, the different information appear.

If a lenticular image contains a metallic motif layer, the motifs shown can be formed by local demetallization of the metallic motif layer. Various ways are known to bring a design into a metallization with a laser by demetallization. On the one hand, demetallization can be effected by direct inscription by guiding a laser beam over the metallic motif layer by means of a suitable scanning device. However, such scanning devices are expensive and usually do not reach the speeds required in an industrial production line.

Another possibility of demetallization is the laser application via a mask. The mask should move in a roll-to-roll process, preferably at the speed of the paper or film web. In addition, each design requires its own mask so that in practice the mask can not simply be printed on the moving web. Alternatively, a separate exposure step must be carried out for each design, with the exposure mask having to be removed from the corresponding direction after laser exposure. In addition, a part of the laser radiation is masked or absorbed by a mask so that only part of the laser intensity is available for the laser inscription itself.

Based on this, the present invention seeks to provide a method of the type mentioned above, which avoids the disadvantages of the prior art, and in particular allows a high production speed and a high efficiency of the Laserdemetallisierung.

This object is solved by the features of the independent claim. Further developments of the invention are the subject of the dependent claims.

• – ein Linsenrasterbild mit einem Linsenraster aus einer Mehrzahl von Mikrolinsen und einer von dem Linsenraster beabstandet angeordneten metallischen Motivschicht bereitgestellt,
• – wird eine Markierungs-Laserquelle zur Erzeugung von gepulster Laserstrahlung bereitgestellt,
• – wird die gepulste Laserstrahlung im Strahlengang zwischen der Laserquelle und dem Linsenrasterbild durch einen Strahlformer oder eine schaltbare Maske mit einem motivförmigen Strahlquerschnitt versehen, und
• – wird eine Mehrzahl von Mikrolinsen des Linsenrasters gleichzeitig mit dem Laserstrahl mit dem motivförmigen Strahlquerschnitt beaufschlagt, um gleichzeitig eine Mehrzahl teilmotivförmig demetallisierter Teilbereiche in der darunterliegenden metallischen Motivschicht zu erzeugen.

According to the invention, in a method of the type mentioned

• A lenticular image is provided with a lenticular array of a plurality of microlenses and a metallic motif layer arranged at a distance from the lenticular grid,
• A marking laser source is provided for generating pulsed laser radiation,
• The pulsed laser radiation in the beam path between the laser source and the lenticular image is provided with a motif-shaped beam cross section by a beam former or a switchable mask, and
• - Is a plurality of microlenses of the lenticular image simultaneously applied to the laser beam with the motif-shaped beam cross-section to simultaneously produce a plurality of partially motive demetallisierter portions in the underlying metallic motif layer.

In an advantageous variant of the method, a diffractive optical element (DOE) or a refractive optical element (ROE) is provided as the beam former. According to a likewise advantageous variant of the method, a micro-mirror actuator (Digital Micromirror Device, DMD) or a surface light modulator (SLM) is provided as a switchable mask.

Both the beamformer and the switchable mask can work in transmission or reflection. It has been found to be particularly advantageous when the beam shaper in transmission or the switchable mask works in reflection.

In the context of this description, microlenses are lenses whose size lies below the resolution limit of the naked eye in at least one lateral direction. The microlenses may be formed, for example, spherical or aspherical. However, the use of cylindrical lenses is currently preferred, so that the method advantageously provides a lenticular image with a lenticular grid of a plurality of micro-cylindrical lenses.

The spherical or aspherical microlenses preferably have a diameter between 5 μm and 100 μm, in particular between 10 μm and 50 μm, particularly preferably between 15 μm and 20 μm. The micro-cylindrical lenses preferably have a width between 5 μm and 100 μm, in particular between 10 μm and 50 μm, particularly preferably between 15 μm and 20 μm. The length of the micro-cylindrical lenses is arbitrary, it may for example correspond to the use of security threads of the total width of the thread and be several millimeters.

Advantageously, in the method, at least 20, preferably at least 50, in particular at least 500 microlenses are acted on simultaneously with the laser beam with the motif-shaped beam cross section.

The microlenses are advantageously acted upon by a laser beam whose beam cross-section is extended over a wide area and which is not limited to a linear surface area. In this case, the beam cross-section in particular has the form of patterns, characters, in particular alphanumeric characters, or a coding.

Furthermore, the microlenses of the lenticular grid are advantageously applied to the laser radiation at an angle for each target image at an angle which corresponds to the predetermined viewing direction of this target image. The microlenses of the lenticular grid can also be exposed to two or more laser beams with a motive beam cross-section from different angles. Alternatively or additionally, the microlenses of the lenticular grid can be exposed to two or more laser beams with different motif-shaped beam cross sections. The two or more laser beams may originate from different marker lasers or from the same marker laser.

Advantageously, the microlenses of the lenticular grid are exposed to pulsed laser radiation having a pulse length between 5 ns and 130 ns. As laser source, an infrared laser in the wavelength range of 0.8 .mu.m to 3 .mu.m, in particular a Nd: YAG laser or Nd: YVO ₄ laser has been proven. In order to locally demetallise certain metals, such as gold or copper, by laser application, shorter wavelengths, in particular in the range from 480 nm to 580 nm, are much better suited. These can be generated, for example, by means of frequency-doubled solid-state lasers.

The laser parameters are advantageously chosen so that the metallic motif layer is locally demetallized by laser ablation by ablation or transparency. The transparency can be effected, for example, by a transformation of the metal of the motif layer into metal oxide, or by a laser-induced melting of the metal layer, in which microscopic metal droplets that are no longer recognizable to the naked eye form.

As a material for the metallic motif layer, aluminum has proven particularly useful, but there are also other metals, such as copper, gold, iron, chromium, nickel, silver, platinum, palladium, titanium, or an alloy of these metals into consideration. In addition to metals and metal alloys, metallic layer-containing thin-film elements with a color shift effect are also suitable for the metallic motif layer. Such thin-film elements typically consist of an absorber layer, a dielectric spacer layer and a metallic reflector layer. The reflector layer is made thin enough so that it can be provided by the laser radiation with the desired partial motive demetallisierten portions.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

Show it:

1 a schematic representation of a banknote with a security element according to the invention in the form of a window security thread, which contains a tilting image with two different target images,

2 schematically the structure of the window security thread of 1 in cross section,

3 schematically a processing device for illustrating the method according to the invention,

4 in (a) to (e) are schematic plan views of a section of the lenticular screen of the 3 or the metallic motif layer in various stages of laser marking, and

5 schematically another processing device for illustrating the method according to the invention.

The invention will now be explained using the example of security elements for banknotes and other value documents. 1 shows a schematic representation of a banknote 10 that with a security element according to the invention in the form of a window security thread 12 is provided. The window security thread 12 occurs in window areas 14 on the surface of the banknote 10 while standing in the intervening land areas 16 inside the banknote 10 is embedded.

In the window areas 14 shows the security thread 12 a tilting image, which the viewer from two different viewing directions 30A . 30B each a different target image 18A respectively. 18B presents. The target images 18A . 18B each show a motif that consists of visually recognizable and contrasting metallic motifs 20 and demetallised motifs 22A . 22B is formed. Specifically, the window security thread shows 12 in the embodiment, when viewed vertically 30A a sequence of coat of arms motifs 22A in front of a shiny metallic background 20 while oblique viewing 30B a sequence of number motifs 22B in the form of the denomination "10" in front of the shiny metallic background 20 can be seen ("negative" motif representation). When the banknote is tilted, the appearance of the window security thread changes 12 in the window areas 14 between the two target images 18A . 18B back and forth. In an embodiment not shown here, alternatively, the subject parts 20 demetallized and the motivational parts 22A . 22B be formed metallic ("positive" motif representation). In the embodiment, the window security thread 12 then when viewed vertically 30A a succession of shiny metallic coat of arms motifs 22A , by oblique observation 30B a sequence of shiny metallic numbers 22B each against a contrasting background 20 demonstrate.

2 shows schematically the structure of the window security thread 12 of the 1 in cross section. The window security thread 12 has a carrier 32 in the form of a transparent plastic film, for example a PET film. The top of the vehicle 32 is with a lenticular grid in the form of a plurality of parallel cylindrical lenses 34 provided, the width b in the embodiment b = 20 microns. On the underside of the carrier 32 is a UV varnish layer 36 arranged on a motif layer 40 made of aluminum, which is in the grid of the cylindrical lenses 34 spaced, demetallized portions 42A . 42B having.

The carrier 32 , the UV varnish layer 36 and the cylindrical lenses 34 are coordinated in the embodiment so that the motif layer 40 in the focal plane of the cylindrical lenses 34 located.

Looking at the window security thread 12 from the vertical viewing direction 30A are because of the focusing effect of the cylindrical lenses 34 only the demetallized subareas 42A and the metallic motif layer surrounding metallic background 40 visible while viewing from the oblique viewing direction 30B only the demetallized subareas 42B and the metallic background surrounding these subregions are visible. Because the demetallized subareas 42A . 42B , as described in more detail below, by means of laser radiation with motive beam cross-section from the directions 30A . 30B into the motif layer 40 were introduced, these sub-areas are set with their metallic background when viewed from the viewing directions 30A . 30B back to the desired sequence of motifs 18A . 18B together.

Because of the small dimensions of the cylindrical lenses 34 works in the reconstruction of the motifs 18A . 18B a large number of demetallised subareas 42A . 42B together. For example, at a height of the demetallized subject parts 22A . 22B of about 2 mm and a width of the cylindrical lenses of b = 20 microns the demetallisierten portions 42A . 42B involved in the reconstruction of the motifs 22A / 20 (Coat of arms) resp. 22B / 20 (Number sequence "10"), over an area of the motif layer 40 which is covered by 2 mm / 20 μm = 100 cylindrical lenses.

As in 2 Also shown is the window security thread 12 typically further layers, such as a full-color layer 44 showing a coloring of the demetallised motif parts 22A . 22B allowed, a cover white layer 46 and a heat sealing lacquer layer 48 , However, these or other functional layers are not essential to the present invention and are therefore not described in detail.

Although laser demetallization of metallic layers is known per se, direct laser marking processes are very time-consuming and therefore generally unsuitable for larger-scale production. To a high To achieve production speed, the laser radiation of a pulsed laser source is provided by a beam former or a switchable mask with a motif-shaped beam cross-section and a plurality of cylindrical lenses within the scope of the invention 34 of the lens grid is acted on simultaneously with the motif-shaped laser beam, so that with a single laser pulse, a plurality teilmotivförmet demetallisierter portions 42A . 42B in the metallic motif layer 40 is produced.

3 shows a processing device to illustrate the process 50 with a marker laser 52 For example, a pulsed Nd: YAG laser with a wavelength of 1.064 microns and a pulse duration between 5 ns and 130 ns. The lenticular screen to be processed 70 is in a working plane 72 arranged and moves at high line speed, for example, 80 m / min in the direction of travel 74 ,

The lenticular screen foil 70 represents a still uncut and not yet demetallised preform of 1 and 2 shown security threads. The lenticular screen 70 has a lenticular grid of a plurality of cylindrical lenses 34 and a spaced-apart metallic motif layer 40 on. The lenticular screen contains a plurality of single-use, which are cut after demetallization in a suitable manner to endless material or singulated to individual use.

The beam cross section of the laser beam 54 initially has a Gaussian or top hat-shaped output intensity distribution, as a rule 56 on, like in 3 shown schematically. The laser beam 54 may optionally be through at least two lenses 58 be widened to the required beam cross section for later processing. The expanded laser beam then passes through a special Demetallisationsbereich to be generated 22A respectively. 22B designed beam former 60 , which is formed in the embodiment by a diffractive optical element (DOE). The diffractive optical element distributes the laser energy in the beam cross section of the laser beam in such a way that the target intensity distribution 62 of the beam cross section in the working plane 72 just the shape and size of the inscribed coat of arms motif 22A or the number of digits to be written "10" (reference numeral 22B ) having.

The redistributed in its cross-sectional intensity laser beam 54 is, optionally by other optical elements such as one or more deflection mirror 64 , Scanner level (not shown) and lenses 66 , on a desired area of the lenticular screen 70 directed in such a way that in the plane of the motif layer 40 , in particular in the focal plane of the cylindrical lenses 34 which gives the correct image of the motif to be written.

The laser beam with its motif-shaped beam cross-section simultaneously acts on a large number of cylindrical lenses 34 , so that the desired motif (crest or number sequence "10" in negative motif representation or background in positive motif representation) each with only a single laser pulse in the metallic motif layer 40 can be enrolled. Because of the short pulse duration within which the lenticular screen foil 70 only moved by a few tens of nanometers, does not have to compensate for the web speed of the lenticular screen during the exposure 70 be made.

The different motives 22A . 22B be on the lenticular screen 70 grid-shaped in several parallel rows, with the positions of the individual motifs 22A . 22B on the lenticular screen 70 and the angles under which the motifs 22A . 22B can be introduced, can be selected in a conventional manner by means of the scanning device, not shown.

The shape of the beam cross section of the laser beam between the beam former 60 and the working level 72 is not important to the present invention. The beamformer 60 only has to be designed so that in the working plane 72 taking into account the beam path between the beam shaper 60 and processing level 72 there the desired target intensity distribution 62 results.

To that in the 1 and 2 To produce the tilted image shown, the crest motif must 22A under vertical laser beam incidence with a first beam former 60 which are in the processing level 72 a target intensity distribution 62 in the form and size of the coat of arms motif to be inscribed 22A generated, and must be the digit string 22B under oblique laser beam incidence with a second beam shaper 60 be generated, which in the working plane 72 a target intensity distribution 62 generated in the form and size of the number sequence "10" ( 3 ). This can be done for example in two machine passes or with a processing device that contains two laser modules or optical modules. It is also possible to divide the radiation of a laser source appropriately and to use it for the two inscription processes. It is understood that it is also possible, the first and second beam shaper 60 For example, in such a way that this instead of the coat of arms motif 22A or the number "10" in the working plane 72 a target intensity distribution 62 in the form and size of each inscribed, the outline of the coat of arms motif 22A or the number sequence forming "10" background 20 generated to thereby realize a "positive" motif representation.

For further explanation shows 4 in (a) to (e) are schematic plan views of a section of the lenticular screen 70 or the metallic motif layer 40 in different stages of laser marking. Referring first to the 4 (a) and (b) is a section of the lenticular screen film, respectively 70 with a plurality of cylindrical lenses 34 shown in plan, in addition, the cross section 62 of the laser beam 54 in the working plane 72 located in, in 4 (a) in the form of the coat of arms (reference numeral 22A in 1 ) and in 4 (b) in the form of the number sequence "10" (reference numeral 22B in 1 ). As shown in the figures, the area of the beam cross section covers 62 each a large number of cylindrical lenses 34 , For example, the beam cross-section is detected 62 at a height of the motives 22A . 22B of 2 mm and a width of the cylindrical lenses of b = 20 microns simultaneously 100 cylindrical lenses.

Due to the focusing effect of the cylindrical lenses 34 The laser radiation is applied to the underlying under the lenticular aluminum motif layer 40 focuses and leads there to a local Demetallisation. The term "demetallization" encompasses both a local ablation and a transparency of the aluminum layer. Transparency can be achieved, for example, by a laser-induced conversion of aluminum into aluminum oxide, or by a laser-induced melting of the aluminum layer in which microscopic droplets that are no longer discernable to the naked eye form.

As a result, laser irradiation with a single laser pulse simultaneously causes a large number of demetallized portions 42A . 42B in the aluminum motif layer 40 generated. 4 (c) and (d) show, for illustration, a plan view only of the motif layer 40 after a laser application with a laser beam with a crest-shaped beam cross-section ( 4 (c) ) or after a laser application with a laser beam with a numerical beam cross section ( 4 (d) ). As can be seen directly from the figures, the beam shaping in the form of motifs can simultaneously produce many, even irregularly shaped partial areas 42A . 42B demetallisiert, and thus a significant acceleration of the manufacturing process can be achieved. The subareas 42A . 42B each have the shape of a part of the motifs 22A . 22B and are therefore referred to in the context of this description as part-motif-shaped sub-areas.

The completeness should be noted that one of the 4 (c) . 4 (d) For better visibility, a fictitious intermediate step in the production of window security thread 12 shows. Will namely the lenticular screen 70 first with the crest-shaped beam cross section 62 applied, as the motif layer indicates 40 when exposed to the numerical beam cross-section 62 already the demetallised parts 42A on. Conversely, the motif layer indicates 40 already demetallised subareas 42B on, if the lenticular screen 70 first with the numerical beam cross section 62 is charged. Because the subareas 42A and 42B are introduced under different directions of action, they are in the plane of the motif layer 40 offset from each other, in particular in 2 shown. The subareas 42A and 42B can also be designed overlapping. In the exemplary embodiment, the width corresponds to the demetalliserten partial areas 42A . 42B therefore ideally half the width of the cylindrical lenses 34 or is slightly larger than this. This makes it possible to achieve a direct transition from one motif to the other when tilting the window.

Overall, in the motif layer 40 by twice the laser exposure, the demetallized portions 42A and 42B introduced, so that in 4 (e) schematically shown appearance arises. In cooperation with the not shown in the figure, above the motif layer 40 arranged grid of cylindrical lenses 34 reconstruct the subareas 42A when viewed vertically, the demetallized coat of arms motif 22A in front of metallic background. When viewed obliquely, the subregions reconstruct 42B the demetallised digit sequence "10" also against a metallic background ( 1 ). The concrete appearance of the demetallised motifs 22A . 22B can by a suitable choice of the color coat 44 ( 2 ) can be set as desired.

It is understood that a Einbelichtung a subject under several loading angles is possible. For example, subjects that should be visible over a wide range of angles can be imprinted at several consecutive angles. Also, more than two target images may be provided, for example, to realize a motion or pumping image when tilting the security element.

Instead of a Diffractive Optical Element (DOE), the beam shaper 60 also be formed by a refractive optical element (ROE). The in 3 exemplified beamformer 60 works in transmission, but it is also possible to use a working in reflection beam shaper, in particular in the form of a reflective diffractive optical element or a reflective refractive optical element.

In a modification of the processing device of 3 shows 5 another processing device 80 in which instead of a beam former 60 a switchable mask 82 is used to generate the motif-shaped beam cross section. As in the embodiment of 3 points the laser beam 54 the pulsed marking laser 52 first a Gaussian or top Hat shaped output intensity distribution 56 on. After the expansion of the laser beam through the lenses 58 the expanded laser beam falls onto the switchable mask 82 , which is formed in the embodiment by a micro-mirror actuator (Digital Micromirror Device, DMD). Such micro-mirror actuators consist of a plurality of individual mirrors arranged in the form of a matrix, each of which is formed by an electronically tiltable mirror surface with an edge length of a few or a few tens of micrometers. Depending on the local position of the mirror surfaces, the laser radiation is passed on (beam component 84 ) or to an absorber 88 deflected (beam proportion 86 ), which absorbs the unnecessary laser energy.

The remaining, provided with a motif-shaped cross-sectional intensity beam component 84 is then as in the embodiment of 3 by further optical elements, such as deflecting mirrors 64 , Scanner level (not shown) and lenses 66 to a desired area of the lenticular screen 70 steered and mapped where the laser beam with the desired target intensity distribution 62 the cylindrical lenses 34 and through this the metallic motif layer 40 applied.

The use of a switchable mask 82 has the particular advantage that different beam cross sections 62 with the same mask 82 can be generated. The mirror surfaces of a micromirror actuator can be brought to a new position within a few microseconds and therefore permit different target images of a lenticular image to be successively imprinted despite the fast-moving web. The disadvantage, however, is that the unneeded part of the laser radiation 86 in the absorber 88 must be deposited so that a stronger laser source than needed for the actual exposure needs to be used.

Instead of micro-mirror actuators, Spatial Light Modulators (SLM) can also be used as a switchable mask, which can redistribute the laser intensity in the beam, and therefore the advantages of a switchable mask (flexibility, possibility to create multiple designs with a mask) Advantages of a beam former (use of the total energy of the laser beam) connect. In this case, on the in 5 Absorbers are dispensed and those of the marking laser 52 Delivered laser energy can be used almost completely for demetallization. Surface light modulators can operate in reflection as well as in transmission, with modulators operating in reflection being presently preferred since they tolerate a higher energy density.

In principle, a switchable mask operating in transmission can also be formed by an LCD display in which the areas to be masked are switched to dark.

LIST OF REFERENCE NUMBERS

10

bill

12

Windowed security thread

14

panes

16

web regions

18A, 18B

target images

20

metallic motif parts

22A, 22B

demetallised motif parts

30A, 30B

viewing directions

32

carrier

34

cylindrical lenses

36

UV lacquer layer

40

motif layer

42A, 42B

demetallized subareas

50

processing device

52

laser marking

54

laser beam

56

Output intensity distribution

58

lenses

60

beamformer

62

Target intensity distribution

64

deflecting

66

lenses

70

Lenticular sheet

72

machining plane

80

processing device

82

switchable mask

84, 86

beam components

88

absorber

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0219012 A1 [0005]

Claims (14)

A method for producing a security element with a lenticular image for displaying one or more target images visible only from predetermined viewing directions, the images of which are formed by visually discernible, contrasting metallic and demetallized portions of a motif layer, wherein in the method Providing a lenticular image with a lenticular of a plurality of microlenses and a metallic motif layer spaced from the lenticular array, Providing a marking laser source for generating pulsed laser radiation, - The pulsed laser radiation is provided in the beam path between the laser source and the lenticular image by a beam shaper or a switchable mask with a motif-shaped beam cross-section, and - A plurality of microlenses of the lens grid is acted upon simultaneously with the laser beam with the motif-shaped beam cross section to simultaneously produce a plurality of partially motive demetallisierter portions in the underlying metallic motif layer. A method according to claim 1, characterized in that a diffractive optical element (DOE) or a refractive optical element (ROE) is provided as a beam shaper. A method according to claim 1, characterized in that as a switchable mask, a micro-mirror actuator (DMD) or a surface light modulator (SLM) is provided. Method according to at least one of claims 1 to 3, characterized in that the beam shaper in transmission or the switchable mask works in reflection. A method according to claim 1 or 3, characterized in that the pulsed laser radiation is provided by a working as a beam former switchable mask with the motif-shaped beam cross-section. Method according to at least one of claims 1 to 5, characterized in that a lenticular image is provided with a lenticular screen of a plurality of micro-cylindrical lenses. Method according to at least one of claims 1 to 6, characterized in that at least 20, preferably at least 50, in particular at least 500 microlenses are acted on simultaneously with the laser beam with the motif-shaped beam cross-section. A method according to at least one of claims 1 to 7, characterized in that the microlenses are acted upon by a laser beam whose beam cross-section is extended flat, and in particular in the form of patterns, characters, in particular alphanumeric characters, or a coding. A method according to at least one of claims 1 to 8, characterized in that the microlenses of the lens grid for each target image are acted upon at an angle with the laser radiation corresponding to the predetermined viewing direction of this target image. Method according to at least one of Claims 1 to 9, characterized in that the microlenses of the lenticular grid are subjected to two or more laser beams with a motive beam cross-section from different angles. Method according to at least one of claims 1 to 10, characterized in that the microlenses of the lenticular grid are subjected to two or more laser beams with different motif-shaped beam cross sections. Method according to at least one of claims 1 to 11, characterized in that the microlenses of the lenticular grid are exposed to pulsed laser radiation having a pulse length between 5 ns and 130 ns. Method according to at least one of Claims 1 to 12, characterized in that the microlenses of the lenticular grid are exposed to an infrared laser in the wavelength range from 0.8 μm to 3 μm, in particular a Nd: YAG laser or an Nd: YVO ₄ laser. Method according to at least one of claims 1 to 13, characterized in that the laser parameters are chosen so that the metallic motif layer is demetallized locally by laser ablation by ablation or transparency.

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