WO2011104330A1

WO2011104330A1 - Marking device and method for marking valuable or security documents with high resolution

Info

Publication number: WO2011104330A1
Application number: PCT/EP2011/052800
Authority: WO
Inventors: Steffen Baudach
Original assignee: Bundesdruckerei Gmbh
Priority date: 2010-02-26
Filing date: 2011-02-25
Publication date: 2011-09-01
Also published as: CN102858552A; CN102858552B; DE102010010070A1; EP2539155A1; EP2539155B1; EP2539155B9

Abstract

The invention relates to a marking device (1) for a valuable or security document (2), and to a method for permanently, more particularly individually, marking valuable and/or security documents (1). The method for permanently marking a valuable or security document (2) comprises the following steps: generating laser light (6) and guiding the laser light (6) by means of a light guiding device (8) such that laser light (6') emerging from the light guiding device (8) is positioned on the valuable or security document (2) and locally marks the valuable or security document (2), wherein the laser light (6) is generated in the form of laser light pulses having a pulse duration of less than 100 ps. As a result, it is possible to utilize non-linear interactions between the material of the valuable or security document (2) and the laser light (6') for marking purposes. Furthermore, given suitable guidance of the laser light (6'), it is possible to achieve improved focusing and, by means thereof, an improved resolution of the patterns produced by means of the marking.

Description

A marking device and method for marking value or security documents with high resolution

The invention relates to a method for marking value or security documents and a marking device, which are designed for permanently marking a value or security document with the aid of laser light.

Security documents are those documents and objects that are protected by at least one security feature or security element against a

Corruption and / or unauthorized copying are protected.

Security documents that embody a value are also referred to as value documents. Security documents include, for example, identity documents, driver's licenses or motor vehicle papers and documents of value, with value documents, for example banknotes, postage stamps or checks.

At least in some of the security documents or value documents, it is advantageous to be able to mark these permanently, preferably individually. Different methods are known from the prior art, with which value and / or security documents can be marked individually. Historically, most value and security documents have been paper-based and, in particular, have been customized by means of printing techniques, modern security documents and value documents are often at least partially made from plastic materials. Modern identity cards and driving licenses are used, for example, as lamination bodies made of several layers of plastic and

optionally combined one or more layers of paper.

For the permanent individual marking of plastics so-called laser marking methods have been developed in the prior art. For this purpose is the

Plastic layers, which consist for example of polycarbonate, special

Pigment substances added at least in individual layers to be later marked with a laser. These do not affect transparency in the visible optical range or are not or barely perceptible to a user. If such a layer is irradiated with laser light of sufficient intensity, an increased absorption of the laser light occurs at the pigments. This makes it possible to use energy in the otherwise coupling transparent plastic, which then leads over the amount of energy deposited here to a local color, for example via heating and a partial carbonization of the plastic material. Depending on the imported

Amount of energy can be set to a degree of blackening of the plastic targeted. From individual local pixels, patterns, in particular grayscale images, lettering and other characters, can be permanently marked in the value or security document.

From DE 100 1 1 486 A1 discloses a card-shaped data carrier is known, consisting of at least one layer in which visually readable information in the form of a change in the optical properties due to an irreversibly caused by a laser beam material change are introduced, the absorption capacity of this layer for at least a wavelength due to the laser radiation is at least partially reduced. In this process, original colored or opaque layers are "bleached" in terms of absorption.

DE 30 48 733 A1 discloses an identification card and a method for producing such an identification card with information applied in the form of patterns,

For example, letters, numbers and / or pictures known. The ID card has differently colored, stacked on at least one surface

Layers areas that are at least partially visible through visually recognizable

Personalization data is interrupted. It is envisaged that the information by the action of a controlled laser beam on one or more on one

Plastic carrier one above the other applied color layers are displayed. As a result of the laser irradiation, the color can be changed locally.

From DE 696 05 788 T2 a method is known for producing an object with a colored mark by irradiating the surface of the object with laser light in the form of the mark, wherein the object consists of a plastic composition in at least the area where the mark is applied containing at least three color-forming components which lose their color-forming ability under the influence of laser light selected and present in a concentration such that at each wavelength between 400 and 700 nm at least part of the amount of incident light is absorbed, For the character one or more colors are chosen, the wavelength of the laser light subsequently set to a value which depends on the selected color and the surface of the object is then irradiated with the laser light.

From WO 01/28778 A2 discloses a method for applying colored characters on a data carrier, preferably made of plastic, known by means of a laser system, wherein in at least one surface layer and / or near-surface layer of the data carrier introduced latent pigments in which by energetic excitation a Changing the absorption behavior is carried out at the designated areas of the data carrier by laser irradiation, which is in the IR and / or visible range, energetically excited in such a way that the same pigments

Color change takes place and that after the color change of the laser-irradiated latent pigments, which are not excited by laser irradiation latent pigments excited by irradiation with light waves in the UV wavelength range energetically such that in the thus irradiated pigments colorlessness is brought about.

From DE 100 53 264 A1 a method for writing data, in particular personalization data, on and / or in a data carrier by means of electromagnetic radiation is known, wherein the method any data carrier is provided on and / or in which at least one colorant at least is provided locally, and this colorant is irradiated by means of the electromagnetic radiation of at least one wavelength range, so that in the field of irradiation a

Changing the color of the colorant by bleaching results, wherein the color change is detectable by machine and / or by a human eye. This results in an increased security against counterfeiting and manipulation for the data carrier.

From DE 199 55 383 A1 a method for applying colored information to an object is known, wherein the object at least in one

near-surface layer has at least two different coloring particles that change the color of this layer under the influence of laser radiation, wherein the laser radiation is used with at least two different wavelengths to change the color of this layer, the application of the object with

Laser radiation in the vector and / or raster method over a

Zweikoordinatenstrahlablenkeinrichtung and a focusing device for focusing the laser radiation on the layer of the object takes place. It is provided at least one beam guiding means to a first laser beam with the wavelength λι and at least one further laser beam having a wavelength λ ₂ , which is different from the wavelength of the first laser beam, to lead to the layer of the object via the two-coordinate beam deflection device and the focusing device. For the

Zweikoordinatenstrahlablenkeinrichtung is proposed an arrangement of two mutually perpendicular axes mounted deflecting mirror. A focusing is done by a fixed plan field optics. Since the light does not pass through the planar field optics on the optical axis, chromatic aberration effects occur in the optical axis

Focusing on. In particular, if differently colored laser light is used for marking, this requires a complex compensation.

From DE 10 2006 014 367 A1 a data carrier and a method for its production are known. The data carrier comprises a visually or machine recognizable marking in the form of a pattern of letters, numbers or pictures. In the method of manufacture, a data carrier with a data carrier substrate

provided and a marking layer applied to the data carrier substrate. The marking is introduced into the marking layer by means of short laser pulses.

From DE 10 2005 001 443 A1 a security marking in a transparent polymer is known. The security marker includes a visually invisible

Diffraction structure inside a transparent polymer produced by multiphoton absorption using ultrashort pulses of a femtosecond laser. The diffraction structure is in the volume of the polymer over

Refractive index changes generated. The extents of the refractive index change are in the submicrometer range. In addition, structures can be generated via multiphoton ablations, the extension of which also lies in the submicrometer range. A readout of the diffraction structure is done with low-power lasers and can be done in transmission or reflection.

In the known from the prior art marking method, which are visually perceptible, it is necessary to mark the plastic material in the

To dope or incorporate paints or pigments, at least if no material removal from the surface of the security document is intended. In such marking methods, too, the pigments to be ablated are generally mixed with pigments or other additives which facilitate laser light absorption. In addition, in the state of the art The technique usually limits an achievable resolution with regard to the marking produced by the fact that the interaction between the laser light and the value or security document is based on thermal effects.

The invention is based on the object, an improved method and an improved device for permanently marking value or

To provide security documents that eliminate or reduce the disadvantages of the prior art.

The object is achieved by a device having the features of claim 1 and a method with the features of claim 5. Advantageous embodiments of the invention will become apparent from the

Dependent claims.

Basic idea of the invention

The basic idea of the invention is the marking of the value and / or

Perform security document with laser light, which is generated with a short pulse laser source. This means that the individual used for marking

Laser light pulses have a pulse duration of less than 100 picoseconds, preferably less than 10 picoseconds. An advantage of using short-pulse laser light is that intensity densities can be achieved with this light, which can also trigger non-linear optical interactions. By way of example, this makes it possible to produce markings with a higher resolution, since thermal interaction processes, which are always associated with a dissipation of the heat into surrounding areas, and in this case a resolution limitation

cause, can be avoided. Furthermore, it is also possible to mark materials that are not separate for laser marking, for example via

Pigment additives or the like, are prepared. Nonlinear effects are exploited here. This gives a greater material independence in the marking. Likewise, diffractive structures can be marked directly in documents. It should be emphasized that a visual impairment of areas adjacent to the introduced markings is omitted. Particularly advantageous, a

Focusing the laser light are performed so that an interaction with material takes place only in focus. Thus, a precise introduction of markings perpendicular to a document surface possible. Also a contribution of

Markings on top of each other, ie in different levels of a document, is possible. With such markings, patterns can be produced which are perceptible in a lateral view. For example, a height of a focused region is preferably about 50 μm. The low damage is also due to the fact that in non-linear processes, which have a quadratic dependence on the intensity (I ² dependence), an interaction outside of a focus drops very rapidly. Introduced near the surface

Marks may be tactile, i. be designed for a tactile perceptible detection.

definitions

A security element is a structural unit comprising at least one security feature. A security element can be an independent structural unit, which can be connected, for example glued, to a security document, which can also be a value document. It can also be an integral part of a security document. An example of the former is a so-called holopatch (a hologram patch, such as a hologram film portion) adhered to a bill, or a visa stickable to a security document. An example of the latter is a diffractive surface relief embossed in an identity document.

A security feature is a structure which can only be produced or reproduced with increased effort (not in comparison to simple copying) or not at all unauthorized, or makes a forgery or falsification visually and / or mechanically recognizable.

As security documents are merely exemplified called identity cards, passports, ID cards, access control cards, visas, tax stamps, tickets, driver's licenses, motor vehicle papers and documents of value, which include banknotes, checks, postage stamps and credit cards, and any smart cards and adhesive labels (eg for product security). Security documents, which also embody a value, are also referred to as value documents. A sharp distinction between these two terms is often not possible. A A credit card, for example, represents a security document protected by security features and security elements against counterfeiting and adulteration, which does not directly represent a value beyond the pure material value of the card, but makes it possible to dispose of large assets.

A pulsed laser is a laser that, in contrast to a continuous wave or CW laser that continuously emits laser light, emits laser light in temporally limited portions called pulses. As a short pulse laser is understood here a laser that generates light pulses whose pulse duration is less than 100 picoseconds. The literature also speaks in part of ultrashort laser pulses, with no uniform definition for this. Ultrashort pulses are pulses whose pulse duration is less than 10 picoseconds.

An optical fiber is a fiber of a transparent material to whose

Total internal reflection can be a conduit of light inside the fiber.

A fiber laser is a laser whose active medium in which light-induced emission of electromagnetic radiation occurs is an optical fiber.

A pattern typically consists of a multiplicity of juxtaposed pattern units or pixel dots. The pattern units or pixels of a pattern are assigned to each other and arranged laterally in a defined manner,

typically in one- or two-dimensional dimensions, and result in the

Overall, a representation, such as an image, a symbol, a logo, a lettering (letters, numbers, alphanumeric characters) or a code (e.g., a bar code). An individualization pattern is a pattern that is used for individualization.

Individualizing is a pattern when it is unique to a person or a person

Is an object or a group of persons or objects from a large totality of persons or objects. For example, a code individualizing a group of persons within the total population of a country is the city of residence. An individualizing for a person code, for example, the number of the identity card or passport photo. One for a group of bills within the total amount of bills individualizing code is the value. Individualizing for a banknote is the serial number. Non-individualizing is a pattern that is identical for all elements of an entity. For bills this is for example a coat of arms, which is printed on all banknotes.

Preferred embodiments

In particular, a marking device for value or security documents is proposed, which at least one laser light source and a

Light guide device which is coupled to the laser light source, so that light of the laser light source is positioned controlled on a value or security document, wherein the laser light source is a short pulse laser source, the laser pulses having a pulse duration of less than 100 picoseconds, preferably less than 10

Picoseconds, generated. Particularly noteworthy is that the short laser pulses via non-linear optical effects with material to be marked value or

Security document interact. Here, a color change, for example, a blackening in different shades of gray, of transparent

Plastic materials possible. A doping with color pigments, which is necessary in the prior art to make the films "laser-capable", is no longer necessary. Thus, visual impairments by the additives necessary for this no longer necessarily occur. A preferred method for permanently marking a value or security document thus comprises the steps: generating laser light and guiding the laser light by means of a light-guiding device, so that from the

Light guide device emitting laser light on the value or

Security document is positioned and the value or security document is marked locally, wherein the laser light is generated in the form of laser light pulses with a pulse duration of less than 100 picoseconds, preferably less than 10 picoseconds.

Particularly advantageous are short laser pulses with pulse durations in the range of less than 100 picoseconds, preferably in the range of 100 Fermtosekunden to 10

Picoseconds, with a fiber laser. Compared with other solid state lasers fiber lasers have the advantage that they can be constructed very compact and have a high electro-optical efficiency. In addition, fiber lasers much more modest in terms of adjustment and handling than most known solid-state lasers.

An advantage of using short laser pulses with pulse durations of less than 100 picoseconds, preferably less than 10 picoseconds, is that a very precise spatial confinement of the interaction zone between the laser light and the material of the asset or security document is achievable when non-linear optical interaction effects can be used to form the label. A preferred embodiment of the method therefore provides that the marking via a non-linear optical effect in the value or

Security document is triggered.

In one embodiment, it is provided that the light-guiding device comprises a relative to the value and / or security document movably mounted optical fiber, which is coupled to at least one drive means so that the light via a movement of an exit surface of the optical fiber in a positioning plane relative to the value - And / or security document can be positioned laterally on the value or security document. The light of the laser light source is thus guided by means of an optical fiber and a positioning of the light on the value to be marked or

Security document is accomplished by moving the exit surface of the optical fiber relative to the asset or security document. Compared to the prior art, there is the advantage that the light used for the marking with a suitable orientation of the positioning plane relative to a surface of the security document, preferably parallel thereto, in each case at the same angle, preferably perpendicular, to the value and / or security document incident and beyond a path length of the traveled light path is the same regardless of the illuminated lateral position on the security and / or security document. This makes it possible to focus the light used more strongly and yet to use an identical focus extension at the marking at all lateral positions of the value or security document. Problems that are known due to a slightly different direction of irradiation in the guide devices of the prior art, can thus be avoided. In a further embodiment it is provided that the value and / or

Security document is mounted movably relative to the optical fiber. Construction and

Use are analogous to that of the moving optical fiber.

In a further embodiment it is provided that both the

Light guide device comprises a relative to the value and / or security document movably mounted optical fiber as well as the value and / or

Security document is movable relative to the optical fiber. It is particularly preferred that the security and / or security document is movable along a transport direction and that the optical fiber is movable in a direction orthogonal to the transport direction, parallel to the surface of the security and / or security document to be personalized.

To achieve a high resolution in the marking, a good focus is advantageous. For this purpose, a focusing optics can be used. It is preferred, a focusing optics, if used, to couple with the respective exit surface of the optical fiber. This means that the focusing optics by means of

Drive device is moved together with the exit surface of the optical fiber. The advantage is that the light path through the focusing optics is the same in each case, regardless of the position on or in the value or security document that is being marked.

In a preferred method, the position of the focus in the document is varied. This means that the focus position along a normal to a plane surface of the document or a plan idealized surface of the value or security document, if this has a surface relief or other irregularities, at the same lateral position or at different lateral positions on the value or security document is varied. Thus, markings are made in different levels of the value or security document. These can be arranged one above the other or laterally offset, in each case arranged relative to the surface of the preferably card-shaped value or security document.

According to one embodiment, marks are generated in the register in different levels in the document. In one embodiment, at least a portion of the Markings perpendicular to the surface of the security or value document considered stacked.

Markers that are marked in different planes parallel to the surface of the value or security document in the value or security document can be used, for example, to display different information for different viewing directions by the markings of the different levels completely or partially in the different viewing directions cover. Furthermore, different layers from which the value or security document is optionally joined together can be connected to one another

be linked in terms of information technology. Individual layers can thus be exchanged or falsified only with difficulty without changing the overall information provided by the three-dimensionally introduced marking.

Different implementations are possible in order to specifically set a focus position in the value or security document.

In one embodiment, the focusing is done by means of the Kerr effect. In this case, the focal length of the material of the focusing lens changes due to the non-linear interaction of the electromagnetic radiation with the material of the lens. The focal length of the lens is inversely proportional to the intensity of the lens

electromagnetic radiation in a gau ßförmigen radiation profile.

In an embodiment in which the light guide is performed by means of an optical fiber, it is provided that in addition to the movement in the positioning plane, which is usually oriented parallel to a surface of a plane security document, a movement of the exit surface of the optical fiber is possible to vary a light path between the exit surface and a surface of the document. This can be used to vary a focus position within the value or security document. Such a change in direction can be achieved, for example, in one embodiment by the fact that the exit surface from which the light is rectilinear to the

Document surface is moved in addition to the movement in the positioning plane, which is selected parallel to the surface of the security or value document, perpendicular to the positioning plane or the surface of the security document or security document. For example, in other embodiments where the exit surface is moved together with imaging and / or focusing optics in the positioning plane to position the exiting light laterally on the surface of the asset or security document, a change in the light path may occur, for example

Embodiments can be achieved in that the exit surface of the

Optical fiber additionally relative to elements of the imaging and / or

Focusing optics, such as a deflection mirror, in the positioning plane is relatively movable. Thus, on the one hand, a positioning laterally on the document via a movement of the exit surface together with the imaging and / or

Focusing optics possible and additionally by a relative movement of the

Exit surface relative to the imaging and / or focusing optics in the positioning plane, a change in the focus position perpendicular to the surface of the value or

Security document possible.

In a further embodiment, the focusing optics consists of a

piezoelectric material. By applying tension, the material can be deformed and thus the focal length of the material can be adjusted.

In a preferred embodiment, the laser light source is integrated in the optical fiber. As a result, any coupling losses are reduced in the coupling into the fiber. Thus, a compact and simple construction is possible. Across from

Solid-state lasers, for example Ti: sapphire lasers, fiber laser systems require no expensive cooling and achieve a high electro-optical efficiency. Furthermore, laser light of different wavelengths can be generated by parametric tuning with the same hardware. This is effective with fiber lasers.

In order to enable a faster marking of the value or security document is provided in a development of the invention that the light guide device comprises at least one further movable, preferably even more movable movably mounted optical fibers. This makes it possible, at the same time at several points or at the same time with different wavelengths of light to attach a mark on the security or security document or in the value or

To introduce security document. If different wavelengths of light are used, then each optical fiber can have one to the corresponding wavelength of light be fitted adjusted focusing optics. It should be noted that with pulse durations of more than 10 ps it is still possible to speak of a defined wavelength. At pulse lengths shorter than 10 ps, the spread due to the Heisenberg uncertainty principle is significant. For example, the blur at a pulse of 10 ps is about 0.41 meV, which corresponds to about 0.12 nm at a wavelength of 620 nm (2 eV). At pulse durations of 10 fs, the blur is about 0.41 eV, which means at a wavelength of 620 nm (2 eV) that the bandwidth is at least 125 nm.

In a preferred embodiment of the invention, the exit surface of the at least one optical fiber is positionable relative to the at least one further optical fiber or optionally relative to the plurality of exit surfaces of the plurality of optical fibers in the positioning plane. Particularly preferred are the plurality

Optical fibers or their exit surfaces in the positioning plane individually driven and positioned relative to each other. It goes without saying for the person skilled in the art that there are mechanical residual actions since the optical fibers can not penetrate one another and thus can not be arranged at one and the same position at the same time.

In one embodiment of the invention, the number of optical fibers is chosen so that upon a relative movement of the entirety of the optical fibers along a

Spacing the entire value or security document or at least a strip of the value or security document can be marked with a two-dimensional / three-dimensional pattern. In this case, the optical fibers can be arranged rigidly relative to one another along a line or any other arrangement.

In one embodiment, it is provided that an optical modifying element is coupled or integrated with the at least one optical fiber, via which the decoupled light can be modified in terms of its frequency and / or intensity. This is particularly advantageous when the light guide device comprises a plurality of further optical fibers. These then preferably also each have an optical modifying element associated with the fiber.

Since the light energy generated by a laser light source is generally sufficient to mark the document at several points at the same time, in one embodiment it is provided that the light from the one laser light source is directed into the at least one laser light source Optical fiber and the at least one further or optionally a plurality of further optical fibers is coupled. Even with such an embodiment, it is advantageous if the individual optical fibers are each assigned an optical change element. It is understood that embodiments are also advantageous, which comprise a plurality of laser light sources whose light is coupled in each case in one or more of the several further optical waveguides.

If a plurality of optical fibers are present, the focus position within the value or security document along a normal to the surface of the value or security document can be set individually for the latter in one embodiment. This can be targeted markings in different levels or layers, from which the value or security document is joined, are introduced. Preferably, this is controlled possible.

The features of the method according to the invention have the same advantages as the corresponding features of the marking device according to the invention.

The invention is based on preferred embodiments below

Reference to a drawing explained in more detail. Hereby show:

Fig. 1 is a schematic representation of a marking device for value or

Security documents;

FIG. 2 shows a further embodiment of a marking device; FIG.

3 shows yet another embodiment of a marking device;

Fig. 4 is a schematic representation of an arrangement of exit surfaces of

Optical fibers relative to a value and / or to be marked

Security document;

5a, 5b an imaging and focusing optics for varying in focus length;

6 is a schematic representation of a beam profile in focus; and Fig. 7 is a schematic representation of a value or security document, are introduced in the markers in different levels.

FIG. 1 schematically shows a marking device 1 for the permanent marking of a value or security document 2. The value document 2 is on a

Bracket 3 is arranged. This can be supplied to the value or security document 2 by means of a transport device 4 and / or removed from it. In some embodiments, it is possible that the transport device 4 forms the holder 3. The person skilled in various devices for transporting value or security documents are known. In general, the marking of the value or security document 2 is carried out after this is completed except for the mark still to be attached. However, it is also possible to make the marking before the value or security document 2 is completely finished, for example, before it is separated from a sheet or a strip.

The marking device 1 comprises a laser light source 5. The laser light source 5 is designed to generate laser light 6. The laser light source 5 is a pulsed light source. For example, it may be a solid state laser, e.g. a Ti: sapphire laser, act. In order to mark the value or security document 2, the laser light 6 must be aimed at the value or security document 2, i. on the surface 7 or inside the value or security document 2, are positioned. For this purpose, a light guide device 8 is provided. In the embodiment described here, the light-guiding device 8 comprises an optical fiber 9, into which the laser light 6 is coupled. An exit surface 10 of the optical fiber 9 is moved in a positioning plane 1 1. The positioning plane 1 1 is formed parallel to the surface 7 of the value or security document 2 in a preferred embodiment. In order to move or position the exit surface 10 in the positioning plane 1 1, the optical fiber 9 is coupled to a drive device 12. The drive device 12 comprises in the illustrated embodiment an X-axis actuator 13, a Y-axis actuator 14 and a Z-axis actuator 15. These are connected and aligned so that the X-axis actuator movement of the exit surface 10 of the optical fiber 9 parallel to a X-axis 16, the Y-axis actuator 14 parallel to a Y-axis 17 and the Z-axis actuator 15 parallel to a Z-axis 18 causes. It should be noted that a movement parallel to the Z-axis causes a change in the positioning plane 1 1. About the

Drive device 12, it is thus possible, a position of a focal point 19 of the exit surface 10 exiting laser light 6 'along a normal to the surface 7 of the value or security document 2 to position. A movement of

On the other hand, the exit surface 10 in the positioning plane 1 1 effects a lateral alignment and positioning of the laser light 6 'emerging from the exit surface 10 or the focal point 19 formed thereof. It should be noted that other embodiments may have and use differently configured light guiding devices

In some embodiments, it is provided that an imaging and / or focusing optics 20 is coupled to the exit surface 10 of the optical fiber 9. This is moved with the exit surface 10 of the optical fiber. In some embodiments, the exit surface 10 of the optical fiber is configured so that the exiting laser light 6 'is focused and no or supplemental focusing optics are necessary. About the introduced in the respective position in the value or security document

Amount of energy, which can be varied, for example, via a pulse intensity or a number of light pulses introduced at the same position, the type of marking, for example a blackening with respect to a gray level, is regulated. Via the drive device 12 it is possible to make a marking vectorially (but broken down into individual pixels (marking points)) or in a grid.

A distance 27 of the positioning plane 1 1 from the surface 7 or the value or security document 2 need not be varied in many applications in the marking. Thus, a positioning device 8 comprising only an X-axis actuator 13 and a Y-axis actuator 14 is sufficient. It is understood by those skilled in the art that for the positioning of the exit surface 10 of the optical fiber 9 in the positioning plane 1 1, a set of actuators can be used, which cause no movements parallel to the coordinate axes, but in interaction are able to

Exit surface 10 in the positioning plane 1 1 lateral position at different locations to position.

It is understood by those skilled in the art that the light exit surface 10 in the

Positioning level 1 1 must not be able to be positioned in all embodiments so that all points on the surface of the document with the exiting laser light 6 'can be illuminated. The laser light only needs to be positionable at those positions on the asset or security document at which markings are to be made. Is only a limited range of value or Security document provided for a mark, as well as an adapted to this area positioning range 26, in which the exit surface 10 of the optical fiber 9 is positioned.

To control the light intensity or even a wavelength of light, is at some

Embodiments integrated a change element in the optical fiber 9 or coupled thereto. The modification element 21 can be designed, for example, as an electro-optical or acousto-optical modulator or switch. Thus, independently of the pulse energy provided by the laser, the locally supplied

Amount of energy and on this example, a blackening in grayscale be controlled.

The individual components of the marking device are controlled by a controller 22, so that the marking is carried out automatically. The controller 22 is only supplied with data containing the pattern for the mark, so that the corresponding areas of the value or security document 2 are irradiated with a corresponding laser light intensity to effect the corresponding marking in the value or security document 2.

The embodiment according to FIG. 1 is characterized in that the laser light 6 is generated as pulsed laser light with short pulse durations of less than 100 ps, preferably less than 10 ps. This is an exploitation of non-linear optical effects for introducing the markings on or in the value or

Security document possible.

By using the optical fiber 9 for guiding the laser light 6 'on or into the security or valuable document 2, a path length 27 between the

Light guide device 8 and the value or security document 2 are kept low. This can be selected in the range from contact to a few cm, preferably 0.2 to 10 mm. This makes it possible to form the beam guide strongly divergent and to focus sharply. Both across the beam direction

(Propagation direction) as well as along the beam direction thus a very narrow focus can be achieved. With suitably chosen intensity and suitably chosen beam profile, a nonlinear interaction is achieved only in a "core region" of the beam of the laser light in the focus, whereby an even closer light focusing is achieved compared to the geometric light focusing

Direction of irradiation of the laser light 6 'as well as longitudinally, that is in

Propagation direction of the laser light 6 'improved resolution can be achieved when marking. For example, micro-writing can be realized with a character size in the range of a few micrometers.

In Fig. 6, a so-called beam profile 61 in focus is shown schematically. A light intensity I is plotted against the position r transversely to the propagation direction (z-direction in FIG. 1), (r is chosen, for example, parallel to the x-axis according to FIG. 1). It is assumed here that a beam profile 61 of the laser light 6 1 (according to FIG. 1) in the focus 19 (according to FIG. 1) has a Gaussian profile. Since nonlinear interactions are dependent on the square I ² 62 of the intensity I of the laser light, that is to say a so-called I ² dependency, the non-linear one is found at a suitably chosen pulse intensity

Interaction takes place only in the core region 63 of the steel profile, in which the square I ² 62 the intensity I of the beam profile 61 exceeds a threshold 64. As a result, the focal extent of the marking is determined by an extension 65 of the core region 63 and not by the extent 66 of the focus 19 of the laser light 6 ', which corresponds to the extent of the beam profile 61.

Due to the possibility of achieving a very good focusing along the direction of propagation (z-direction in FIG. 1) of the laser light 6 ', it is via a variation of the focus position, for example via a variation of the distance 27 between the

Exit surface 10 of the optical fiber 9 and the value or security document 2 or its surface 7, possible to mark high-resolution markers in different planes. It is assumed here that the planes are oriented parallel to the surface 7. It is for example card-shaped value or

Security documents which have an extent of 500 μm to 1000 μm perpendicular to the surface 7 make it possible to mark a plurality of mutually separate markings 71 ', 71 "in register along a surface normal 72 to the surface 7. Likewise, the markings 71 in the different planes 73-79, but laterally offset with respect to the surface 7 of the document of value or document 2, as is schematically shown in Fig. 7, which are arranged vertically above one another arranged separately formed markings 71 ', 71 "can be marked by the same surface 7 and arranged for example above the opaque plane 77.

In addition to a marking by causing discoloration in the value or security document, other material changes can be brought about, for example, causes a scattering or diffraction of light in the ultraviolet and / or visible and / or infrared wavelength range.

2, a further embodiment of a marking device 1 is shown schematically. Technically equivalent features are provided with identical reference numerals. The illustrated embodiment differs from that of FIG. 1 in that the light guide device 8 in this embodiment two

Optical fibers 9, 9 'comprises. These are respectively coupled to a drive device 8 or 8 ', which are formed analogously to the drive device 8 according to FIG. This embodiment offers the advantage that the value or security document 2 can be marked simultaneously or quasi simultaneously at several locations.

The laser light source 5 is shown schematically in this embodiment as a fiber laser 23 with a seed laser 24 and an amplifier ring 25. It will be understood by those skilled in the art that another source of laser light may be used with it

Embodiment can be used. Likewise, a fiber laser 23 as

Laser light source 5 are used in the embodiment of FIG. 1.

The emerging from the laser light source 5 light 6 is either a beam splitter (not shown) divided and coupled into the optical fiber 9, 9 'simultaneously or via an electro-optical or electro-acoustic switch alternately in the

Optical fibers 9, 9 'coupled. Since the mechanical movement speed of the exit surfaces 10, 10 'via the drive means 8, 8' are usually limited, can at a suitable selected repetition rate of the laser light 6, 6 'even at maximum movement speed of the exit surfaces 10, 10' is a mark of the value or Security document 2 take place, even if every second laser pulse in the other optical fiber 9, 9 'is coupled. In this case, marking is still considered to be simultaneous or quasi-simultaneous. In Fig. 3, another embodiment of a marking device 1 is shown schematically. In this embodiment, two laser light sources 5, 5 'are provided. This makes it possible in a simple manner, in different places with

different repetition rates, wavelengths, etc. markings on or in the value or security document 2 contribute.

In Fig. 4, the exit surfaces 10 of a further embodiment of a marking device are shown schematically schematically, in which a plurality of optical fibers 9 coupled to each other via a drive means together relative to the value or security document 2 are movable. In such an embodiment, large-area markings can be accomplished in a short time. Also in this embodiment, each of the optical fiber 9 is preferably one

Variation element (not shown) is coupled so that the respective coupled laser light intensity and / or laser frequency can be controlled via each optical fiber 9.

Compared with the use of solid-state lasers, such as, for example, Ti: sapphire lasers, a fiber laser system can be used to achieve higher electro-optical efficiencies. Thus, the required energy can be significantly reduced. The entire structure can be made much more compact, so that fitting into a production line or plant is much easier. In addition, as fiber laser systems require less maintenance and installation effort, laser marking systems can also be deployed remotely.

Shown in Figures 5a and 5b is an embodiment in which focus positioning, i. a positioning of the focal point parallel to the Z-axis, analogous to the geometry of FIG. 1 is described. The embodiment includes an imaging and

Focusing Optics 20 This includes a focusing lens 31 and a deflecting mirror 32. In addition, a focusing actuator 33 is provided. About this, a relative movement between the deflecting mirror 32 and the exit surface 10 of the optical fiber 9 can be effected. This changes the focus position along the Z-axis. Overall, the imaging and focusing device 20 is moved together with the exit surface 10 of the optical fiber in the positioning plane 1 1, which coincides with the XY plane, to laterally position the laser light 6 'on the value or security document. In addition, a movement of the light exit surface 10 in the positioning plane 1 1 is also effected via the Fokussieraktor 33, which, however, only the distance changed to the deflecting mirror 32 and this the focus position perpendicular to the positioning plane.

LIST OF REFERENCE NUMBERS

1 marking device

2 value or security document

3 bracket

4 transport device

5 laser light source

6, 6 'laser light

7 surface

8, 8 'light guide device

9, 9 'optical fiber

10, 10 'exit surface

1 1 positioning plane

12, 12 'drive device

13, 13 'X-axis actuator

14, 14 'Y-axis actuator

15, 15 'Z-axis actuator

16 X axis

17 Y-axis

18 Z axis

19 focus point

20 Imaging and / or focusing optics

21 element of change

22 control

23 fiber lasers

24 seed lasers

25 amplifier ring

26 positioning range

27 distance

31 lens

32 deflection mirror

33 Focusing factor

61 beam profile

62 square of intensity (I ² )

63 core area threshold

Extension of the core area Extension of the focus marks

surface normal

levels

Claims

claims

1 . Marking device (1) for value or security documents comprising

at least one laser light source (5),

a light guide device which is coupled to the laser light source so that laser light (6) of the laser light source can be positioned controlled on a value or security document (2),

characterized in that

the laser light source (5) is a short pulse laser source which generates laser pulses with a pulse duration of less than 100 ps.

2. marking device (1) according to claim 1, characterized in that the laser light source (5) comprises a fiber laser (23).

3. marking device (1) according to claim 1 or 2, characterized in that the light guiding device (8) relative to the value or security document (2) movably mounted optical fiber (9), which comprises at least one

Drive device (12) is coupled so that the laser light (6 ') via a

Movement of an exit surface (10) of the optical fiber (9) in a positioning plane (1 1) laterally on the value or security document (2) can be positioned.

4. marking device (1) according to claim 3, characterized in that the exit surface (10) of the at least one optical fiber (9) relative to the surface (17) of the value or security document (2) is movable so that a focus position ( 19) of the laser light (6 ') inside the value or

Security document (2) is variable.

5. A method for permanently marking a value or security document (2) comprising the steps:

Generation of laser light (6) and

Guiding the laser light (6) by means of a light guiding device (8) so that the laser light (6 ') emerging from the light guiding device is positioned on the security document (2) and

the value or security document (2) is marked locally, and characterized in that laser light (6) is generated in the form of laser light pulses with a pulse duration of less than 100 ps.

6. The method according to claim 5, characterized in that the laser light (6)

is guided by means of an optical fiber (9) and a positioning of the laser light (6 ') on the value or security document (2) to be marked via a

Movement of an exit surface (10) of the optical fiber (9) relative to the value or security document (2) takes place.

7. The method according to claim 5 or 6, characterized in that the laser light (6) by means of a fiber laser (23) is generated.

8. The method according to any one of claims 5 to 7, characterized in that a focus position (19) of the laser light (6 ') in the interior of the value or

Security document (2) is variable to in the value or

Security document (2) to create markers in the register at different levels (72-78).

9. The method according to any one of claims 5 to 8, characterized in that the marking (71) via a non-linear optical effect in the value or security document (2) is triggered.

10. The method according to any one of claims 5 to 9, characterized in that

at least two markings (71) formed separately from one another perpendicular to the surface (7) of the security or security document (2) are marked one above the other by the same surface (7) in the security document (2).

1 1. Method according to one of claims 5 to 10, characterized in that

Markings (71) are introduced as diffractive and / or scattering structures into the interior of the word or security document (2).

12. The method according to claim 1 1, characterized in that by means of the laser light (6) a local modification of the refractive index of a material of the value or security document (2) is effected to introduce the diffractive and / or scattering structure.