Abstract:
An ID document comprises a receiving substrate in or on which an ink that is fluorescent under UV-A lighting is locally deposited, and a multilayer optical security component attached to a substrate. The optical component comprises a structurable layer and a reflective dielectric layer discontinuously deposited on the structurable layer in the plane of the component so as to produce patterns. The reflective dielectric layer has a relative transmission of at most 40% in the UV-B or UV-C range. The optical component also include an assembly of at least one layer including pigments that are fluorescent when energized by UV-B or UV-C. These are deposited on the reflective dielectric layer in a uniform or discontinuous manner in the plane of the optical component.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the field of increasing security via multilayer films. 
         [0002]    Such multilayer films, also called optical security components, are said to be security films because they are used to increase the security of identity documents, in particular documents such as passports and identity cards; to increase the security of fiduciary documents, in particular such as banknotes; or even to increase the security of valuable items; “documents” below for the sake of conciseness. 
         [0003]    In the case of identity documents or fiduciary documents, a multilayer film is placed on the document or integrated into the document. In the case of valuable items, the multilayer film is integrated into a security label that is placed on said valuable item or on its packaging. 
         [0004]    To increase the security of documents, it is known to deposit locally an ink  107  that is fluorescent under illumination in the UV-A on an optical component carrier or a carrier that is optionally integrated into or onto a paper carrier, this being advantageous in that such a deposition allows patterns that become visible and that are readable by machine or a human being under suitable illumination to be drawn. 
         [0005]    The present invention aims to provide an alternative and to increase the security of documents by virtue of a multilayer film comprising pigments that are fluorescent under UV-B and/or UV-C excitation, independently of the presence or absence of ink  107  that is fluorescent under illumination in the UV-A. 
         [0006]    Furthermore, the present invention provides a new effect for inspecting a transparent security component via a perfect registration between zones of high-optical index, observable under illumination in the visible (spectral band 400-800 nm), and zones including pigments that are fluorescent in the visible under UV-B and/or UV-C excitation. 
       SUMMARY OF THE INVENTION 
       [0007]    More precisely, the invention relates, according to a first of its subject matters, to an identity document comprising:
   an assembly of at least one destination carrier ( 301 ) in which or on which an ink ( 107 ) that is fluorescent under illumination in the UV-A is deposited locally, and   a multilayer optical security component placed on a destination carrier ( 301 ).   
 
         [0010]    This identity document is essentially characterized in that the optical component furthermore comprises:
   a structurable layer ( 102 ) that is deposited on the carrier film ( 101 ); and   a dielectric reflective layer ( 103 ) that is deposited on the structurable layer ( 102 ) discontinuously in the plane of the component, so as to produce dielectric zones allowing patterns ( 202 ) to be drawn; the dielectric reflective layer ( 103 ) having a relative transmittance in the UV-B or UV-C domain at most equal to 40%; and   an assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation, said assembly being deposited on said dielectric reflective layer ( 103 ) uniformly or discontinuously in the plane of the optical component.   
 
         [0014]    Provision may furthermore be made for a partially demetallized metallic layer ( 105 ) deposited on the structurable layer ( 102 ) or on the dielectric reflective layer ( 103 ). 
         [0015]    Provision may furthermore be made for: a protective layer ( 106 ) that is selectively deposited on the metallic layer ( 105 ). 
         [0016]    Provision may be made for the protective layer ( 106 ) to be halftone, so as to comprise islands the shape and size and the spacing between two adjacent islands of which are preset. 
         [0017]    Provision may be made for the dielectric reflective layer ( 103 ) to locally make contact with the structurable layer ( 102 ) or contact with the protective layer ( 106 ), so that said optical component locally comprises one stack among:
   a successive stack of the carrier film ( 101 ), of the structurable layer ( 102 ) and of assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation;   a successive stack of the carrier film ( 101 ), of the structurable layer ( 102 ), of the dielectric reflective layer ( 103 ), and of assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation;   a successive stack of the carrier film ( 101 ), of the structurable layer ( 102 ), of the dielectric reflective layer ( 103 ), of the metallic layer ( 105 ), of the protective layer ( 106 ), and of assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation; and   a successive stack of the carrier film ( 101 ), of the structurable layer ( 102 ), of the metallic layer ( 105 ), of the protective layer ( 106 ), of the dielectric reflective layer ( 103 ), and of assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation.   
 
         [0022]    Provision may be made for the structurable layer ( 102 ) to comprise an assembly of structures allowing an optically variable image to be generated. 
         [0023]    Provision may be made for a detachment layer ( 109 ) deposited between the structurable layer ( 102 ) and the carrier film ( 101 ), and allowing, by thermal activation, the structurable layer ( 102 ) to be subsequently separated from the carrier film ( 101 ). 
         [0024]    Provision may be made for the assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation to be composed:
   of a layer ( 1042 ) of ink that is fluorescent under UV-B or UV-C excitation, said layer being coated with a layer of glue ( 1043 ); or   of a first adhesive layer ( 1041 ), a layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation, which layer is deposited on the first adhesive layer ( 1041 ), then a second adhesive layer ( 1043 ) deposited on the layer ( 1042 ); or   of one and the same layer ( 1042 ) including pigments that are fluorescent under UV-B or UV-C excitation, also having adhesive properties.   
 
         [0028]    Provision may be made for the dielectric layer ( 103 ) to be halftone, so as to comprise islands the shape and size and the spacing between two adjacent islands of which are preset. 
         [0029]    Provision may be made for the multilayer optical security component furthermore to comprise at least one among:
   an assembly of at least one zone ( 107 ) including pigments that are fluorescent under UV-A excitation; and   a carrier layer ( 101 ), not detachable from the structurable layer ( 102 ).   
 
         [0032]    According to another of its subject matters, the invention also relates to a process for manufacturing an optical security component, the process comprising steps consisting in:
   depositing a structurable layer ( 102 ) on a carrier film ( 101 ) made of plastic or of paper, the carrier film ( 101 ) and the structurable layer ( 102 ) being adjacent to or separated from each other by an assembly of at least one technical layer,   depositing on the structurable layer ( 102 ) an assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent when they are exposed to a light source emitting in the UV spectrum, and   uniformly depositing a dielectric reflective layer ( 103 ).   
 
         [0036]    This process is essentially characterized in that it furthermore comprises steps consisting in, sequentially:
   locally depositing on the structurable layer a layer ( 108 ) of varnish or ink that is soluble in a liquid, in the form of zones making contact with the structurable layer ( 102 ) drawing patterns ( 201 ) when they are observed at least in reflection,   depositing said dielectric reflective layer ( 103 ) on the layer ( 108 ) of varnish or ink that is soluble in a liquid, and at least partially in contact therewith,   disaggregating the soluble ink ( 108 ) by submerging the optical component in said liquid, in order to locally remove the dielectric reflective layer ( 103 ) in the location of each zone of soluble varnish ( 108 ) in order to reproduce said patterns ( 201 ) in said disaggregated dielectric reflective layer ( 103 ); and   depositing said assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent when they are exposed to a light source emitting in the UV spectrum on the dielectric reflective layer ( 103 ) and in contact therewith.   
 
         [0041]    Provision may furthermore be made for a step consisting in: subjecting the optical component to a mechanical stress during its submergence, in particular using ultrasound. 
         [0042]    Provision may furthermore be made for a step consisting in: depositing an assembly of at least one technical layer between the carrier film ( 101 ) and the structurable layer ( 102 ), in particular a detachment layer ( 104 ) allowing, by thermal activation, the carrier film ( 101 ) to able to be subsequently separated from the structurable layer ( 102 ). 
         [0043]    Preferably, the step consisting in depositing said assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent when they are exposed to a light source emitting in the UV spectrum on the dielectric reflective layer ( 103 ) and in contact therewith comprises depositing at least one layer ( 1042 ) including pigments that are fluorescent when they are exposed to a light source emitting in the UV-B or UV-C spectrum. 
         [0044]    Provision may be made for a step consisting in depositing said layer ( 1042 ) uniformly or selectively on the optical component. 
         [0045]    Preferably, the step consisting in depositing said assembly ( 1040 ) of at least one layer ( 1042 ) including pigments that are fluorescent when they are exposed to a light source emitting in the UV spectrum on the dielectric reflective layer ( 103 ) and in contact therewith comprises at least one of the steps consisting in:
   coating said layer ( 1042 ) with a layer of glue;   depositing said layer ( 1042 ) on a first adhesive layer ( 1041 ) and in contact therewith, then coating said layer ( 1042 ) with a second adhesive layer ( 1043 ); and   integrating into said layer ( 1042 ), prior to its deposition, adhesive components.   
 
         [0049]    Provision may furthermore be made for steps consisting in:
   uniformly depositing a metallic layer ( 105 ) on the optical component, subsequently to the step consisting in depositing said dielectric reflective layer ( 103 );   depositing a protective layer ( 106 ) directly in contact with the metallic layer ( 105 ), selectively in the form of zones drawing patterns when they are observed at least in reflection;   demetallizing the metallic layer ( 105 ) by dissolving zones of the metallic layer ( 105 ) that are not protected by the protective layer ( 106 ), drawing patterns when they observed at least in reflection.   
 
         [0053]    Provision may furthermore be made for steps consisting in, prior to the step consisting in depositing said dielectric reflective layer ( 103 ):
   uniformly depositing a metallic layer ( 105 ) on the optical component;   depositing a protective layer ( 106 ) directly in contact with the metallic layer ( 105 ), selectively in the form of zones drawing patterns when they are observed at least in reflection;   demetallizing the metallic layer ( 105 ) by dissolving zones of the metallic layer ( 105 ) that are not protected by the protective layer ( 106 ), drawing patterns when they observed at least in reflection.   
 
         [0057]    Preferably the optical component furthermore comprises a hologram. In this case, the zones of the layer ( 108 ) of varnish or ink that is soluble in a liquid making contact with the structurable layer ( 102 ) are deposited in register with said hologram, so that the patterns ( 201 ) reproduce the outline of said hologram. 
         [0058]    Provision may be made for zones ( 202 ) corresponding to those zones of the optical component for which the dielectric layer ( 103 ) has been preserved; the method furthermore comprising a step consisting in generating a halftone effect in the zones ( 202 ), by deposition of the protective layer ( 106 ) on the metallic layer ( 105 ) or deposition of the dielectric layer ( 103 ) selectively so as to create islands the shape and size and the spacing between two adjacent islands of which are preset. 
         [0059]    Other features and advantages of the present invention will become more clearly apparent on reading the following description, which is given merely by way of nonlimiting illustrative example and with reference to the appended figures. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0060]      FIG. 1  illustrates a cross section of a multilayer film according to the prior art; 
           [0061]      FIGS. 2A to 2D  sequentially illustrate in cross section a first embodiment of an optical component according to invention, 
           [0062]      FIGS. 3A to 3G  sequentially illustrate in cross section a second embodiment of an optical component according to invention, 
           [0063]      FIGS. 4A to 4F  sequentially illustrate in cross section a third embodiment of an optical component according to invention, 
           [0064]      FIG. 5A  illustrates a view in reflection of an optical component according to the invention illuminated by a source of visible light, 
           [0065]      FIG. 5B  illustrates a view in reflection of the optical component of  FIG. 5A  illuminated by a source of UV-A light, 
           [0066]      FIG. 5C  illustrates a view in reflection of the optical component of  FIG. 5A  illuminated by a source of UV-C light, 
           [0067]      FIG. 6  illustrates the variation in the transmittance of a layer of ZnS as a function of its thickness, and 
           [0068]      FIGS. 7A and 7B  illustrate two stages of production of one embodiment of an optical component according to the invention, comprising a hologram. 
       
    
    
     DETAILED DESCRIPTION 
       [0069]    For the sake of simplicity, here “optical component” and “multilayer film”; “ink” and “varnish”; “film” and “layer” have been equated. 
         [0070]    Likewise, an optical component is here described as being planar. Depending on its constituent materials, it may nevertheless have a certain degree of flexibility, in particular when the optical component takes the form of a self-adhesive label. 
         [0071]    By UV-A what is meant is the spectrum 315-400 nm, by UV-B what is meant is the spectrum 280-315 nm and by UV-C what is meant is the spectrum 100-280 nm. 
         [0072]    A multilayer security film is intended to be observed at least in reflection. It comprises a front face and a back face ( FIG. 1 ). By convention, the expression “front face” is defined as the face via which the optical component can be illuminated in reflection and the expression “back face” is defined as the face that is intended to make contact with a for example paper, polycarbonate, PVC or plastic carrier, called a “destination” carrier, and for example via an adhesive. The destination carrier may possibly moreover be transparent or have a lower opacity than that of the optical component. 
         [0073]    Moreover, the relative position of certain layers may have an influence on the optical effects of said component. During the manufacture of the film, at least certain layers are therefore deposited in a preset order in order to provide the optical security component with its optical properties, as described below. 
         [0074]    In the context of the present invention, by convention, a cross section of the optical component is considered to be oriented so that the bottom of the optical component corresponds to the front face, i.e. the structurable layer  102  or the carrier film  101 , and so that the top of the optical component corresponds to the back face, i.e. the layer  104  or the assembly  1040 , which are described below. Thus, if a given layer A is deposited on another given layer B, what is meant by “deposited on” is the fact that the layer A is located above the layer B in cross section, without however necessarily making contact therewith. In terms of manufacturing process, this means, unless otherwise specified, that the layer A is deposited subsequently to the layer B. 
       Prior Art 
       [0075]      FIG. 1  illustrates a cross section of a conventional multilayer film intended to be placed on a document  300  comprising a destination carrier  301 . Its manufacturing process is as follows. 
         [0076]    On a carrier film  101  made of plastic, essentially allowing the optical component to be manufactured and typically polyethylene terephthalate (PET) or equivalent, a structurable layer  102  is deposited. The carrier film  101  essentially serves to manufacture the optical component. The layer  102  is said to be “structurable” in that it is capable of locally including structures, i.e. protrusions and recesses, the dimensions (in particular the height) of which are typically comprised between one nanometer and one micron, and that influence the reflection, diffraction or scattering of an incident electromagnetic wave. The layer  102  is said to be “structured” when it includes such structures. For example, the structurable layer may be structured by hot stamping a thermoformable varnish or by cold molding and UV curing of an ad hoc varnish (casting varnish) to give the layer  102 . 
         [0077]    Moreover, the carrier film  101  and the structurable layer  102  may be adjacent or separated from each other by an assembly of at least one what is called “technical layer”, such as for example what is called a “detachment” layer  109  allowing, during thermal activation, the carrier film  101  to be subsequently separated from the structurable layer  102 . 
         [0078]    During the manufacture of the optical component, a layer of zinc sulfide (ZnS)  103  of thickness comprised between 10 and 500 nm is deposited by vacuum thermal evaporation or by any other suitable method (electron-beam evaporation, etc.). This layer  103  of ZnS uniformly covers the entirety of the surface of the component, i.e. all the surface of the structurable layer  102 . 
         [0079]    Certain multilayer films furthermore comprise local zonewise deposits of an ink  107  that is fluorescent under UV-A excitation. Alternatively, the zones of an ink  107  that is fluorescent under UV-A excitation may be deposited not on the multilayer film but on the destination carrier  301 , as illustrated in  FIG. 1 . 
         [0080]    The zones of fluorescent ink typically allow a pattern that is observable in reflection to be drawn. 
         [0081]    Next, a technical layer  104  is coated over all the layer of ZnS  103 . When the component comprises zones of fluorescent ink  107 , said zones are also covered by the technical layer  104 . The technical layer  104  may be an adhesive layer comprising an adhesive material; and/or a protective layer, for example comprising a varnish. 
         [0082]    Invention 
         [0083]    A new and extraordinarily ingenious way of producing similar patterns is proposed here. 
         [0084]    To this end, provision is made for the absolute value of the variation in refractive index between the structurable layer  102  and the dielectric reflective layer  103  to be higher than or equal to 0.5. Furthermore, the advantageously high-refractive-index dielectric reflective layer  103  has a relative transmittance in the UV-B and/or UV-C domain at most equal to 40% and is discontinuous in the plane of the component so as to produce dielectric zones allowing patterns to be drawn. Provision is then made to coat this dielectric reflective layer  103  with an assembly  1040  of at least one layer  1042  including pigments that are fluorescent under UV excitation and in particular UV-B or UV-C excitation, as described below. 
         [0085]    The term “fluorescent” is used for the sake of conciseness. In the context of the present invention, the term “fluorescent” must be understood to mean “photoluminescent”, i.e. to also encompass phosphorescence. 
         [0086]    In all the embodiments below, provision is made for a structurable layer  102  to be deposited on a carrier film  101 , in the present case one made of plastic. 
         [0087]    The structurable layer  102  and the carrier film  101  may make direct contact with each other, as illustrated. Provision may also be made for an assembly of at least one technical layer between the structurable layer  102  and the carrier film  101 . For example what is called a “detachment” layer  109  allowing, by thermal activation, the structurable layer  102  to be subsequently separated from the carrier film  101  is deposited between the structurable layer  102  and the carrier film  101 , as illustrated in  FIG. 1 . 
       First Embodiment 
       [0088]    A first embodiment is illustrated in  FIGS. 2A to 2D . 
         [0089]    As illustrated in  FIG. 2A , provision is made to selectively deposit, in the present case by printing, in particular by rotogravure, a partial layer of soluble varnish  108  (for example an ink based on polyvinyl alcohol) on the structurable layer  102  and preferably in direct contact with the latter. The selective deposition in the form of zones of soluble varnish  108  makes it possible to draw patterns  201  when they are observed at least in reflection. 
         [0090]    Provision is then made to cover the component, in the present case the structurable layer  102  and the zones of soluble varnish  108 , with a dielectric reflective layer  103  (typically of ZnS or TiO 2 ), as illustrated in  FIG. 2B . 
         [0091]    Once the dielectric reflective layer  103  has been deposited by any known means, provision is made to disaggregate the layer  108 , for example by submerging the optical component in a suitable bath, i.e. a bath containing a solution that disaggregates the soluble varnish  108  when it makes contact therewith. The destruction of the layer  108  results in the dielectric reflective layer  103  being removed locally from locations of each zone of soluble varnish  108 , as illustrated in  FIG. 2C . Such techniques are known, for example from document U.S. Pat. No. 6,896,938. Provision may furthermore be made to subject the optical component to a mechanical stress during its submergence, for example via a step consisting in subjecting the optical component to ultrasound, this facilitating the disaggregation of the soluble ink  108 . 
         [0092]    Thus, the pattern  201  drawn by the disaggregated zones of the dielectric reflective layer  103  reproduces the pattern  201  drawn by the zones of varnish  108  before their dissolution, this being why these two patterns have here been referenced with the same reference number. As explained below, the pattern  201  is observable by fluorescence when it is illuminated by a light source emitting in the UV spectrum, but less visible when it is illuminated by a light source emitting in the visible spectrum. 
         [0093]    Provision is then made to coat the optical component with an assembly  1040  of at least one layer  1042  including pigments that are fluorescent under UV excitation, below “the” layer  1040  for the sake of conciseness, see  FIG. 2D . By “pigments that are fluorescent under UV excitation” or even “UV-fluorescent ink”, what is meant is that the pigments (or the ink comprising such pigments) are fluorescent when they are exposed to a light source emitting in the UV and in particular the UV-B or UV-C wavelength domain. 
         [0094]    The assembly  1040  may consist of at least one of the following variants: 
         [0095]    In a first variant, the assembly  1040  is composed of a layer  1042  of ink that is fluorescent under UV excitation, said layer being coated with a layer of glue  1043 . 
         [0096]    In a second variant, the assembly  1040  is composed of a first adhesive layer  1041 , a layer  1042  of ink that is fluorescent under UV excitation, then a second adhesive layer  1043 . 
         [0097]    In a third variant, the assembly  1040  is composed of one and the same layer  1042  of ink that is fluorescent under UV excitation, also having adhesive properties. 
         [0098]    The layer  1042  of UV-fluorescent ink may be applied uniformly to the optical component, in which case the pattern  201  appearing in observation under UV light corresponds to the pattern formed by the disaggregated zones of the dielectric reflective layer  103 , the pattern of which advantageously corresponds to the pattern of the dissolved soluble varnish  108  ( FIG. 2D ). 
         [0099]    The layer  1042  of UV-fluorescent ink may be applied selectively to the optical component, thereby creating zones of UV-fluorescent ink allowing patterns to be drawn when they are observed in reflection under UV illumination. In this case, under UV illumination a combination of the pattern drawn by the layer  1042  of UV-fluorescent ink and of the pattern  201  drawn by the disaggregated zones of the dielectric reflective layer  103  is observed, the fluorescence being observable only in the zones printed with UV-fluorescent ink that are not covered by the reflecting zones of dielectric reflective layer  103 . 
         [0100]    Thus, observation of the optical component in reflection in UV light allows an image to be generated that is observable on three levels: an absence of UV-fluorescent ink, a UV-fluorescent ink filtered by the dielectric, and a UV-fluorescent ink. 
         [0101]    The structurable layer  102  may make direct contact with zones of dielectric reflective layer  103 , make direct contact with zones  1042  of UV-fluorescent ink, or contact with a first adhesive layer  1041 . 
         [0102]    The lower face (reflection side) of the assembly  1040  of at least one layer  1042  including pigments that are fluorescent under UV excitation makes direct contact with the structurable layer  102  or direct contact with a zone of dielectric reflective layer  103 . 
         [0103]    In this embodiment, the optical component may therefore locally comprise one of the following stacks: 
         [0000]    a successive stack of the layers  101 ,  102 ,  1040 ; or
 
a successive stack of the layers  101 ,  102 ,  103 ,  1040 .
 
         [0104]    Second Embodiment 
       A second embodiment is illustrated in FIGS.  3 A to  3 G. 
       [0105]    In the second embodiment, provision is made, as in the first embodiment illustrated in  FIG. 2A , to selectively deposit a partial layer of soluble varnish  108  (for example an ink based on polyvinyl alcohol) on the structurable layer  102 , and preferably directly in contact therewith, and in the present case by printing, in particular rotogravure. The selected deposition in the form of zones of soluble varnish  108  allows patterns to be drawn when they are observed at least in reflection. 
         [0106]    Provision is then made to cover the component, in the present case the structurable layer  102  and the zones of soluble varnish  108 , with a dielectric reflective layer  103  (typically ZnS or TiO 2 ), as illustrated in  FIG. 2B . 
         [0107]    Once the dielectric reflective layer  103  has been deposited by any known means, provision is made to submerge the optical component in order to disaggregate the soluble ink  108  which, via its destruction, locally removes the dielectric reflective layer  103  in line with each zone of soluble varnish  108 , as illustrated in  FIG. 2C . Such techniques are known, for example from document U.S. Pat. No. 6,896,938. Provision may furthermore be made to subject the optical component to a mechanical stress during its submergence, for example via a step consisting in subjecting the optical component to ultrasound, this facilitating the disaggregation of the soluble ink  108 . 
         [0108]    Thus, the pattern drawn by the zones of the disaggregated dielectric reflective layer  103  reproduces the pattern drawn by the zones of varnish  108  before their dissolution. The embodiments illustrated in  FIGS. 2A, 2B and 2C  are therefore identical to the embodiments illustrated in  FIGS. 3A, 3B and 3C , respectively. 
         [0109]    In the second embodiment, provision is then made to deposit a metallic layer  105  that is applied uniformly to the optical component, which has the advantage of having optical properties that are visually different such as for example opacity, reflectivity and/or enhanced diffraction, and/or of allowing plasmonic effects that require the presence of a metallic layer. 
         [0110]    Provision is then made to selectively deposit a protective layer  106 , in the present case a varnish, in direct contact with the metallic layer  105 , as illustrated in  FIG. 3E . The selective zonewise deposition of protective layer  106  allows patterns (not illustrated) to be drawn. 
         [0111]    Provision is then made to demetallize the metallic layer  105 , in the present case by submerging the optical component in a caustic soda solution. 
         [0112]    The zones of the metallic layer  105  not protected by the protective layer  106  are then dissolved, as illustrated in  FIG. 3F , thereby also allowing a pattern (not illustrated) to be created by the demetallization of the metallic layer  105 . 
         [0113]    Next, as in the first embodiment, provision is made to coat the optical component with an assembly of at least one layer including pigments that are fluorescent in the visible under UV excitation  1040 , below “the” layer  1040  for the sake of conciseness. 
         [0114]    The assembly  1040  may consist of at least one of the following variants. 
         [0115]    In a first variant, the assembly  1040  is composed of a layer  1042  of UV-fluorescent ink that fluoresces in the visible under UV excitation, said layer being coated with a layer of glue. 
         [0116]    In a second variant, the assembly  1040  is composed of a first adhesive layer  1041 , a layer  1042  of UV-fluorescent ink that fluoresces in the visible under UV excitation (for example a coated protective layer), then a second adhesive layer  1043 . 
         [0117]    In a third variant, the assembly  1040  is composed of one and the same layer  1042  of UV-fluorescent ink that fluoresces in the visible under UV excitation, also having adhesive properties (see  FIG. 3G ). 
         [0118]    In this embodiment, the assembly  1040  is applied uniformly to the optical component, in which case the pattern  204  appearing in observation under UV-B or UV-C light corresponds to the pattern formed by the zones of the disaggregated dielectric reflective layer  103 , the pattern of which advantageously corresponds to the pattern of the dissolved soluble varnish  108 , with the exception of the metallized zones ( FIG. 3G ). 
         [0119]    The structurable layer  102  may make direct contact with zones of dielectric reflective layer  103 , direct contact with the assembly  1040  comprising zones of UV-fluorescent ink, or contact with those zones of the metallic layer  105  which are protected by the protective layer  106 . 
         [0120]    Those zones of the metallic layer  105  which are protected by the protective layer  106  make direct contact therewith. They may either make contact with the structurable layer  102 , or are stacked on zones of dielectric reflective layer  103 . 
         [0121]    The upper face of the structurable layer  102  makes contact with zones of dielectric reflective layer  103 , with the assembly  1040  of at least one layer including pigments that are fluorescent the assembly  1040  under UV excitation, or makes contact with zones of the metallic layer  105 . 
         [0122]    The upper face of the zones of the metallic layer  105  makes direct contact with the protective layer  106 . 
         [0123]    The lower face (reflection side) of the zones of the metallic layer  105  makes contact with the structurable layer  102  or contact with zones of dielectric reflective layer  103 . 
         [0124]    In this embodiment, the optical component may therefore locally comprise one of the following stacks: 
         [0000]    a successive stack of the layers  101 ,  102 ,  1040 ;
 
a successive stack of the layers  101 ,  102 ,  103 ,  1040 ; or
 
a successive stack of the layers  101 ,  102 ,  103 ,  105 ,  106 ,  1040 .
 
         [0125]    The second embodiment advantageously allows, with respect to the first embodiment, a stack of zones of the metallic layer  105  making direct contact with the protective layer  106  to be added locally, thereby allowing additional patterns, visible in reflection, to be drawn by virtue of the partially demetallized metallic layer  105 . 
       Third Embodiment 
       [0126]    A third embodiment is illustrated in  FIGS. 4A to 4F . 
         [0127]    Provision is made to deposit a metallic layer  105 , which is applied uniformly to the optical component, in the present case directly in contact with the structurable layer  102 , as illustrated in  FIG. 4A . 
         [0128]    Directly in contact with the metallic layer  105 , provision is then made to selectively deposit a protective layer  106 , in the present case a varnish, as illustrated in  FIG. 4B . The selective zonewise deposition of protective layer  106  allows patterns to be drawn. 
         [0129]    Provision is then made to demetallize the metallic layer  105 , for example by submerging the optical component in a caustic soda solution. Demetallization, or partial metallization, is for example known from document U.S. Pat. No. 5,145,212. 
         [0130]    The zones of the metallic layer  105  not protected by the protective layer  106  are then dissolved, as illustrated in  FIG. 4B . 
         [0131]    Provision is made to selectively deposit, in the present case by printing, in particular by rotogravure, a partial layer of soluble varnish  108  (for example an ink based on polyvinyl alcohol) in contact with the structurable layer  102  or in contact with at least one zone of protective layer  106 , see  FIG. 4C . The selective deposition in the form of zones of soluble varnish  108  allows patterns to be drawn when they are observed at least in reflection. 
         [0132]    Provision is then made to cover the component, in the present case the structurable layer  102 , the zones of soluble varnish  108 , and those zones of the metallic layer  105  which are protected by the zones of the protective layer  106 , with a dielectric reflective layer  103  (typically ZnS or titanium dioxide (TiO 2 ), as illustrated in  FIG. 4D . 
         [0133]    Once the dielectric reflective layer  103  has been deposited by any known means, provision is made to submerge the optical component in order to disaggregate the soluble ink  108  that, via its destruction, locally removes the dielectric reflective layer  103  in the locations of each zone of soluble varnish  108 , as illustrated in  FIG. 4E . 
         [0134]    Thus, the pattern drawn by the zones of the disaggregated dielectric reflective layer  103  reproduces the pattern drawn by the zones of varnish  108  before their dissolution (ignoring the metallized zones). 
         [0135]    Provision may furthermore be made to subject the optical component to a mechanical stress during its submergence, for example via a step consisting in subjecting the optical component to ultrasound, thereby facilitating the disaggregation of the soluble ink  108 . 
         [0136]    Next, as in the first embodiment, provision is made to coat the optical component with an assembly of at least one layer including pigments that are fluorescent in the visible under UV excitation, below “the” layer  1040  for the sake of conciseness. 
         [0137]    The assembly  1040  may consist of at least one of the following variants. 
         [0138]    In a first variant, the assembly  1040  is composed of a layer  1042  of UV-fluorescent ink that fluoresces in the visible under UV excitation, said layer being coated with a layer of glue  1043 . 
         [0139]    In a second variant, the assembly  1040  is composed of a first adhesive layer  1041 , a layer  1042  of UV-fluorescent ink that fluoresces in the visible under UV excitation (for example a coated protective layer), then a second adhesive layer  1043 . 
         [0140]    In a third variant, the assembly  1040  is composed of one and the same layer  1042  of UV-fluorescent ink that fluoresces in the visible under UV excitation, also having adhesive properties (see  FIG. 4F ). 
         [0141]    In this embodiment, the assembly  1040  is applied uniformly to the optical component, in which case the pattern appearing in observation under UV light corresponds to the pattern formed by the zones of the disaggregated dielectric reflective layer  103 , the pattern of which advantageously corresponds to the pattern of the dissolved soluble varnish  108  ( FIG. 4F ), ignoring the metallized zones. 
         [0142]    The structurable layer  102  may make direct contact with zones of dielectric reflective layer  103 , direct contact with the assembly  1040  comprising zones of UV-fluorescent ink, or contact with those zones of the metallic layer  105  which are protected by the protective layer  106 . 
         [0143]    The upper face of the zones of the metallic layer  105  makes direct contact with the protective layer  106 . 
         [0144]    The lower face (reflection side) of the zones of the metallic layer  105  makes contact with the structurable layer  102 . 
         [0145]    The upper face of the zones of the dielectric reflective layer  103  makes direct contact with the assembly  1040  comprising zones of UV-fluorescent ink. 
         [0146]    The lower face (reflection side) of the zones of the dielectric reflective layer  103  makes direct contact with the structurable layer  102 , or direct contact with the protective layer  106 . 
         [0147]    The upper face (transmission side) of the protective layer  106  may make contact with at least one of the zones of the dielectric reflective layer  103  or direct contact with the assembly  1040  comprising zones of UV-fluorescent ink. 
         [0148]    In this embodiment, the optical component may therefore locally comprise one of the following stacks: 
         [0000]    a successive stack of the layers  101 ,  102 ,  1040 ;
 
a successive stack of the layers  101 ,  102 ,  103 ,  1040 ; or
 
a successive stack of the layers  101 ,  102 ,  105 ,  106 ,  103 ,  1040 .
 
         [0149]    The third embodiment advantageously allows, with respect to the second embodiment, the position of the zones of the dielectric reflective layer  103  to be locally inverted with respect to the stack of zones of the metallic layer  105  making direct contact with the protective layer  106 , thereby making it possible not to subject the dielectric deposition to the step of demetallization of the metal, which may cause deterioration of the layer. 
       Application to a Security Document 
       [0150]    Whatever its embodiment, an optical component according to the invention is advantageously integrated into any security document, for example an identity document a passport, etc. or a fiduciary document, for example a banknote. It may take the form of a label for adhesively bonding to a product or a valuable item. 
         [0151]    Security documents  200  possess a destination carrier in paper or plastic form that incorporates patterns  203  that are visible only under illumination by a light source emitting in the UV-A ( FIG. 5B ). 
         [0152]    Preferably, the dielectric used for the reflective layer  103  is ZnS, and the ink used for the layer  1042  is a UV-fluorescent ink that fluoresces in the visible under UV-C or UV-B excitation because ZnS filters by absorption the UV-B and UV-C, as illustrated in  FIG. 6  which is an experimental curve produced by the applicant. 
         [0153]      FIG. 6  illustrates the variation in the relative transmittance of the fluorescence emitted by a layer  1042  the thickness and the concentration in pigments of which have been normalized, through a layer of ZnS, as a function of the thickness of the layer of ZnS, and for three values of wavelength: a wavelength λ=250 nm (UV-C), a wavelength π=300 nm (UV-B) and a wavelength λ=350 nm (UV-A). Such pigments are for example known from documents WO2014048702 and WO2009005733. 
         [0154]    The decrease in transmittance as a function of thickness clearly illustrates the filter effect exerted by the layer of ZnS. The fluorescence emitted by the pigments under UV-C is lower than the fluorescence emitted by the pigments under UV-B, which itself is lower than the fluorescence emitted by the pigments under UV-A. 
         [0155]    Empirically, it is estimated that below a relative transmittance equal to 40%, the fluorescence is no longer observable. Thus, for thicknesses of layer  103  comprised between 20 nm and 140 nm, said layer  103  is indeed a spectral filter blocking the fluorescence of the pigments of the layer  1042  under UV-B or UV-C whereas the fluorescence of the pigments if any of the ink  107  remain observable. Assuming that a destination carrier comprises an ink  107  containing pigments that are fluorescent under UV-A illumination and that the optical component according to the invention is locally superposed with at least one partial layer  107 , the presence of dielectric  103  according to the invention is no obstacle to the reading of the pattern drawn by the zones of ink  107  under UV-A illumination. The optical component according to the invention is therefore compatible with the presence of such inks in a destination carrier or in said optical component. 
         [0156]    Under UV-C or UV-B illumination, the ZnS screens the fluorescence of the ink of the layer  1042 , and therefore only the patterns  201  of any one of the preceding embodiments give rise to a fluorescence visible in the form of fluorescent patterns  204 . 
         [0157]    The zones or patterns  201  correspond to those zones of the optical component for which the dielectric  103  has been locally removed and the zones or patterns  202  correspond to those zones of the optical component for which the dielectric  103  has been preserved. 
         [0158]    Thus, as the manufacturer of the proposed optical component has no control over the position of the patterns  203  visible under UV-A illumination, the creation of a pattern visible in UV-C and/or UV-B advantageously makes it possible not to hinder the reading of said patterns  203  under UV-A illumination, and reciprocally, that the patterns  203  visible under UV-A illumination do not disrupt the reading of the patterns  201  visible under UV-C and/or UV-B illumination. 
       Hologram 
       [0159]    Provision may be made for the multilayer film to furthermore comprise an area containing an optically variable image, also called a hologram or holographic image  205 , i.e. an assembly of microstructured zones of the structurable layer  102  that are designed to produce an optically variable visual effect also known as a DOVID (Diffractive Optical Variable Image Device), this in itself increasing the security of the optical component. 
         [0160]    The DOVID, commonly called a “hologram” (not illustrated), observable in visible light, is generated by stamping the structurable layer  102  and is visible on the finished product only in the zones including a reflective layer (metallic layer  105  or high-refractive-index layer  103 ) i.e. in one of the zones  202 . In the zones of the optical component where the layer  102  makes direct contact with the assembly  1040 , the grating is said to be “blocked” and the holographic image is no longer observable. 
         [0161]    The surface of the hologram and the pattern  201  visible in UV may be complementary (unless metal is present) with each other. 
         [0162]    Provision may advantageously be made for the zones of soluble varnish  108  to be deposited in register with the hologram. To this end, provision may be made for the soluble varnish  108  to be slightly colored in order to facilitate the positioning. 
         [0163]    Thus, by virtue of the invention, it is possible to create a pattern visible in UV-C and/or UV-B that is identical in its contours and in its position to the hologram, by depositing soluble ink  108  in register with the hologram. 
         [0164]    Without this solution, the falsification of a security document comprising a hologram and an identical pattern visible in UV would typically consist in superposing a layer comprising the pattern in UV-fluorescent ink on the holographic layer of the optical component. However, such a superposition is never perfect if only because of the mechanical tolerances at play. 
         [0165]    In contrast, the invention allows the hologram to be perfectly outlined in UV-C and/or UV-B because the hologram and pattern  201  visible in UV are both generated in the same manufacturing process, this increasing the security level of the optical component. 
         [0166]    Preferably, provision is made in this case for the lateral extension D 2  of the hologram  205  to be smaller than the lateral extension D 1  of the structured zone of the structurable layer  102  liable to bear said hologram. 
         [0167]    To this end, the ink  108  may be partially deposited on the structured zone of the layer  102  ( FIG. 7A ), this giving, after deposition of the dielectric layer  103  and disaggregation of the ink  108 , a hologram  205  the outline of which is fluorescent ( FIG. 7B ) when it is illuminated by a UV-B or UV-C source, via the zones  201 . 
         [0168]    To check the authenticity of the document, provision may be made for steps consisting in illuminating the document with visible light and recording the position of the hologram in a memory, illuminating the document with UV-C and/or UV-B and recording the position of the pattern  201  in a memory, and then comparing the two images, and in particular their position. 
       Halftones 
       [0169]    In the second and third embodiment, provision may furthermore be made for the protective layer  106  to be selectively deposited on the metallic layer  105  so as to create islands the shape and size and the spacing between two adjacent islands of which are preset, thereby typically allowing a halftone effect to be generated in the zones  202  comprising dielectric. 
         [0170]    Provision may also be made for the dielectric layer  103  to be halftone, i.e. 
         [0171]    selectively deposited so as to create islands the shape and size and the spacing between two adjacent islands of which are preset, thereby making it possible to create all sorts of small areas that are meaningless in visible light but that form a pattern that has meaning under UV-B or UV-C illumination. 
       Transparency 
       [0172]    According to the invention, the carrier layer  101 , when it is not detachable from the optical component, the structurable layer  102 , the dielectric reflective layer  103  and the assembly  1040  of at least one layer including pigments that are fluorescent under UV excitation are preferably at least partially transparent in the visible, so that data carried by the document  300  may be recognized optically when the optical component is placed on the document and the latter is illuminated in the visible domain. 
       NOMENCLATURE 
       [0173]      100  Optical component 
         [0174]      101  Carrier layer 
         [0175]      102  Structurable layer 
         [0176]      103  (ZnS, TiO2, etc.) dielectric reflective layer 
         [0177]      104  Technical layer 
         [0178]      105  Metallic layer 
         [0179]      106  Protective layer protecting the metallic layer 
         [0180]      107  Partial layer of ink that is fluorescent under UV-A excitation 
         [0181]      108  Layer of varnish or of ink that is soluble in a liquid 
         [0182]      200  Security document 
         [0183]      201  Pattern drawn by the zones of the disaggregated dielectric reflective layer, or pattern drawn by the zones of varnish  108  before their dissolution, in visible light, seen in reflection 
         [0184]      202  Pattern corresponding to those zones of the optical component for which the dielectric  103  has been preserved, seen in reflection 
         [0185]      203  Pattern visible only under illumination with a light source emitting in the UV-A 
         [0186]      204  Pattern  201  that is fluorescent, illuminated with UV-C light 
         [0187]      205  DOVID: structured zone of the structurable layer making contact with the dielectric reflective layer 
         [0188]      300  Document 
         [0189]      301  Destination carrier 
         [0190]      1040  Assembly of at least one layer including pigments that are fluorescent under UV-B or UV-C excitation 
         [0191]      1041  First adhesive layer 
         [0192]      1042  Layer including pigments that are fluorescent under UV-B or UV-C excitation 
         [0193]      1043  Second adhesive layer