PhD defense Manuel Flores"Materials and nanostructuring processes on flexible supports for personalized security features"

"Materials and nanostructuring processes on flexible supports for personalized security features"

Abstract:

The development of laser printers and copiers makes document forgery increasingly powerful. These technologies can produce almost identical surface level features as real ones. Forgers tend to alter a user’s portrait as it is the most unique feature of an ID document. Therefore, a particular focus is set on developing complex technologies enabling the production of portraits easily observable by anyone, but also highly secure. Our lab’s Nanoparticles team has recently demonstrated the potential of plasmonic materials to produce interesting effects for anti-counterfeiting purposes. For instance, processing silver nanoparticles embedded in a semiconductor titania matrix (Ag:TiO2) with femtosecond or nanosecond laser results in the formation of well-defined nanostructures. These metasurfaces, depending on the laser processing conditions, present a wide variety of optical effects detectable in different observation and illumination conditions. However, these effects have mainly been exploited on rigid transparent substrates (e.g. glass) which are not suitable for industrial applications. In fact, ID documents being mainly composed of plastic and paper supports, this thesis work aims at implementing Ag:TiO2 films in a plastic card to produce interesting color effects by laser processing. Color algorithms previously established are utilized and adapted to produce several demonstrators, with full-color images easily visible with the naked eye. Additionally, multiplexing was achieved by encoding two images in a single print.

Jury:

• Nathalie Destouches, Hubert Curien Lab, Supervisor
• Francis Vocanson, Hubert Curien Lab, Co-supervisor
• David  Grosso, Univ. Aix Marseille, Co-supervisor
• Laurence Bois, Univ. Lyon 1, Examiner
• Tatiana Itina, Hubert Curien Lab, Examiner
• Jérome Plain, Univ. de Technologie de Troyes, Reviewer
• Olivier Soppera, Institut de Science des Matériaux de Mulhouse, Reviewer
• Stéphane Ayala, HID Global, Invited
• Nipun Sharma, HID Global, Invited